Triarylmethyl radicals and the use of inert carbon free radicals in MRI

ABSTRACT

A radical compound of formula Ia 
     
         .C(Ar.sup.12).sub.3                                        (Ia) 
    
     wherein: 
     each Ar 12 , which may be the same or different, represents a 6-membered carbocyclic, at least one group Ar 12  being a group Ar 1  ; 
     each group Ar 1  represents a 6-membered ring optionally substituted at the or any ortho carbon by a group R 1 , R 2 , R 3  or R 4 , at the or any meta carbon by a group R 2  or R 3 , and at any para carbon by a group R 1 , R 2 , R 3  or R 4 , 
     with the proviso that no more than two ring carbons are unsubstituted; 
     each of R 1 , R 2 , R 3  or R 4 , which may be the same or different, independently represents a group of formula --M, --XM, --XAr 2  or --Ar 2  ; 
     M represents a water solubilizing group, each group X, which may be the same or different, represents an oxygen or sulphur atom or a NH or CH 2  group.

The present invention relates to the use of stable free radicals, inparticular inert carbon radicals, as image enhancing agents in magneticresonance imaging (MRI) as well as to contrast media containing suchradicals and to the use of such radicals and their non-radicalprecursors in the manufacture of MRI contrast media.

MRI is a diagnostic technique that has become particularly attractive tophysicians as it is non-invasive and does not involve exposing thepatient under study to potentially harmful radiation, such as forexample the X-radiation of conventional radiography.

This technique, however suffers from several serious drawbacks,including in particular the expense of manufacture and operation of theMRI apparatus, the relatively long scanning time required to produce animage of acceptable spatial resolution, and the problem of achievingcontrast in the magnetic resonance (MR) images between tissue typeshaving the same or closely similar imaging parameters, for example inorder to cause a tissue abnormality to show up clearly in the images.

The expense of manufacture and operation of an MRI apparatus is closelyassociated with the strength of the magnetic field that the primarymagnet in the apparatus is required to generate in order to produceimages of acceptable spatial resolution in an acceptable time.

MR images are generated by manipulation of the MR signals detected fromthe sample, for example a human or animal body, placed in a magneticfield and exposed to pulses of radiation of a frequency (typicallyradiofrequency (RF)) selected to excite MR transitions in selectednon-zero spin nuclei (the "imaging nuclei", which are generally waterprotons in body fluids) in the sample.

The amplitude of the induced MR signals is dependent upon variousfactors such as the strength of the magnetic field experienced by thesample, the temperature of the sample, the density of the imaging nucleiwithin the sample, the isotopic nature and chemical environment of theimaging nuclei and the local inhomogeneities in magnetic fieldexperienced by the imaging nuclei.

Thus many techniques have been proposed for enhancing MR image quality,for example by increasing MR signal amplitude or by increasing thedifference in MR signal amplitude between different tissue types.

The imaging parameters (nuclear density, T₁ and T₂) for tissues ofinterest may be altered and many proposals have been made for doing thisby the administration of magnetically responsive materials into patientsunder study (see for example EP-A-71564 (Schering), EP-A-133674(Schering) and WO-A-85/04330 (Jacobsen)). Where such materials,generally referred to as MRI contrast agents, are paramagnetic theyproduce significant reduction in the T₁ of the water protons in the bodyzones into which they are administered or at which they congregate, andwhere the materials are ferromagnetic or superparamagnetic (for exampleas suggested by Jacobsen) they produce a significant reduction in the T₂of the water protons. In either case the result is enhanced (positive ornegative) contrast in the MR images of such zones.

The contrast enhancement achievable by such agents in conventional MRIis relatively limited and it is generally not such as to allow areduction in the image acquisition period or in the field strength ofthe primary magnet.

Utilisation of the spin transition coupling phenomenon known as dynamicnuclear polarisation or as the Overhauser effect to amplify thepopulation difference between the ground and excited spin states of theimaging nuclei by the excitation of a coupled ESR transition in aparamagnetic species present in the sample being imaged has beendescribed by Hafslund Nycomed Innovation AB in WO-A-88/10419.

This new technique for generating a MR image of the sample, which ishereinafter termed electron spin resonance enhanced magnetic resonanceimaging (ESREMRI), or Overhauser MRI, involves exposing the sample to afirst radiation of a frequency selected to excite nuclear spintransitions in selected nuclei in the sample (radiation which isgenerally of radiofrequency or thereabouts and thus for convenience willbe referred to hereinafter as RF radiation) and also exposing the sampleto a second radiation of a frequency selected to excite electron spintransitions coupled to nuclear spin transitions for at least some of theselected nuclei (radiation which is generally of microwave frequency orthereabouts and thus for convenience is referred to hereinafter as MW orUHF radiation), the MR images being generated from the resultingamplified MR signals (free induction decay signals) emitted by thesample.

The paramagnetic substance which possesses the ESR transition whichcouples with the NMR transition of the image nuclei may be naturallypresent within the imaging sample or more usually may be administered asan ESREMRI contrast agent.

In WO-A-88/10419 various ESREMRI contrast agents were proposed, for themost part these being nitroxide stable free radicals, although the useof chloranil semiquinone radical and of Fremy's salt was also proposed.

In WO-A-90/00904 Hafslund Nycomed Innovation AB proposed the use ofdeuterated stable free radicals, in particular deuterated nitroxidestable free radicals, as ESREMRI contrast agents.

Organic free radicals however frequently have properties which renderthem unsuitable for use as ESREMRI contrast agents. Thus free radicalscommonly are unstable in physiological conditions, or have very shorthalf-lives leading to toxicity problems. A further drawback is the lowrelaxivity exhibited by many free radicals, which results in poorcoupling of the electron and nuclear spin transitions and thus a poorenhancement of the magnetic resonance signal. A need therefore existsfor improved free radical ESREMRI contrast agents.

The ESREMRI contrast agents so far proposed in the literature have allbeen "oxygen free radicals" that is to say radicals where the unpairedelectron or electrons are associated with oxygen atoms.

We have now surprisingly found that carbon free radicals, i.e. radicalswhere the unpaired electron or electrons are primarily associated withcarbon atoms are particularly attractive for use as ESREMRI contrastagents.

For such free radicals to be effective, they should be relatively longlived and to distinguish from free radicals which have a momentaryexistence, those usable as ESREMRI contrast agents will be referred toherein as being "inert" free radicals, that is having a half life of atleast one minute at ambient temperature.

Viewed from one aspect the present invention thus provides the use of aninert carbon free radical for the manufacture of a contrast medium foruse in ESREMRI.

Viewed from a further aspect, the invention also provides a method ofmagnetic resonance investigation of a sample, said method comprisingintroducing into said sample an inert carbon free radical, exposing saidsample to a first radiation of a frequency selected to excite electronspin transitions in said free radical, exposing said sample to a secondradiation of a frequency selected to excite nuclear spin transitions inselected nuclei in said sample, detecting free induction decay signalsfrom said sample, and, optionally, generating an image or dynamic flowdata from said detected signals.

Viewed from a still further aspect, the invention also provides amagnetic resonance imaging contrast medium comprising a physiologicallytolerable inert carbon free radical together with at least onepharmacologically acceptable carrier or excipient.

For in vivo imaging, the inert carbon free radical should of coursepreferably be a physiologically tolerable radical, or one presented in aphysiologically tolerable, e.g. encapsulated, form.

Inert carbon free radicals are well known and a range of these has beendescribed for example by Ballester et al. (see JACS 93: 2215 (1971), J.Org. Chem. 47:259-64 and 4498 (1982), 48 3716 (1983), 53 1267-73 (1980),54 4811-15 (1989), Accounts of Chemical Research 18:380 (1985) andreferences therein); Fox et al. (see JACS 109, 7088-94); Gomberg, JACS22, 757 (1900); Neunhoffer Chem. Ber., 91, 1801 (1958); Maki, Chem.Phys, 35, 761 (1963); Dunnebacke, Chem. Ber. 122 533 (1989); JundeikisJACS 84 1132 (1961); Sinclair, JACS 90 5074 (1968); Bent, JACS 84 3250(1932); Falle, Canad. J. Chem. 44 1387 (1966); Ziegler, Annalen 458 248(1927); Allan, JCS (1936) 440; Acta (Chem. Scand. 16 1817 (1962);Theilacker, Annalen 594 214 (1955); Muller, Angew. Chem. 5 6 (1966);Schlenck, Annalen 372 1 (1910); Teilacker, Angew. Chem. 69 322 (1957);Sabacky, JACS 89 2054 (1967); Muller, Tetrakedron Lett 3877, (1967);Marvel JACS 66 415 (1944); and Trapp, J. Chem. Phys 45 3472 (1966).

Preferred inert carbon free radicals for use according to the inventionexhibit high stability to oxygen, to pH, for example in the range pH5-9, and in aqueous solution, particularly stability up to aconcentration of 300 mM. Further desirable characteristics includereduced tendency to dimerization, long half-life, preferably greaterthan 1 minute, particularly preferably greater than 1 hour andespecially preferably 1 year, long relaxation times, both T_(1e) andT_(2e) preferably being greater than 1 μsec, high relaxivity, forexample greater than 0.3 mM⁻¹ sec⁻¹ and a small number of esr transitionlines.

Particularly preferred inert carbon free radicals include thesubstituted methyl radicals, in particular triarylmethyl radicals whereeach of the three aromatic substituent groups may be the same ordifferent and where two or three such groups may optionally be linkedtogether. Particularly preferably the radical comprises optionallysubstituted six-membered carbocyclic or heterocyclic aromatic ringsoptionally carrying one or more fused carbocyclic or heterocyclic rings.

The possibility exists to optimize different characteristics, e.g.solubility, stability, line broadening, of the overall radical byappropriate combinations of different aryl substituents on the methylcarbon. Combinations, where two such aryl substituents, preferablyidentical, are selected to optimize stability and line broadening, andone aryl substituent is selected to optimize solubility are consideredparticularly interesting.

In order to optimize the above-mentioned desirable properties, a numberof criteria need to be borne in mind in selecting or constructingtriarylmethyl radicals for use according to the invention.

Thus, the aromatic rings of the triarylmethyl radical advantageously aresubstituted and the nuclear identities of nuclei in all substituents andtheir position within the molecule should be selected so as to minimisetheir effect (line splitting or broadening) on the esr transition.

In such cases, a six-membered aromatic ring is preferably substituted atthe ortho and para positions. This is desirable in order to minimisedimerisation and oxygen attack on the molecule. The meta position isoptionally substituted, preferably with a bulky substituent, again tominimise attack by oxygen and at least one of the substituents shouldconveniently comprise a water solubilizing moiety. Such substituentspreferably have no magnetic moment, or have a very low effective spindensity. Alternatively, in order to minimise their effect on the esrtransition, the substituents should be bonded in such a manner that theyare capable of free rotation.

Particularly preferred inert carbon free radicals include thetriarylmethyl radicals of formula I

    .C(Ar.sup.1).sub.3                                         (I)

(where each group Ar¹, which may be the same or different, is preferablya substituted thienyl, phenyl, 4-pyridinyl, 3-pyridinyl, 2-pyridinyl,5-pyrimidyl or 4-pyrimidyl group). Other preferred triarylmethylradicals include those of formula Ia

    (Ar.sup.12).sub.3 C.                                       (Ia)

where each Ar¹², which may be the same or different, comprises anoptionally substituted 5-7 membered carbocyclic or heterocyclic aromaticring optionally carying one or more fused carbocyclic or heterocyclicrings, one or more such Ar¹² groups preferably being a group Ar¹ asdefined herein.

Particularly preferably each group Ar¹ represents a 6 memberedcarbon-attached carbocyclic or heterocyclic aromatic ring containing upto 2 non-adjacent ring nitrogens optionally substituted at the or anyortho carbon by a group R¹ to R⁴, at the or any meta carbon by a groupR² or R³ and at any para carbon by a group R¹,R²,R³ or R⁴, with theproviso that no more than two ring carbons are unsubstituted, preferablyonly one ring carbon at most being unsubstituted;

each of R¹ to R⁴, which may be the same or different, independentlyrepresents a group of formula --M, --XM, --XAr² or --Ar² ; M representsa water solubilizing group, each group X, which may be the same ordifferent, represents an oxygen or sulphur atom or a NH or CH₂ group;

Ar² represents a 5 to 10 membered aromatic ring optionally substitutedby a solubilizing group M;

or groups R¹ and/or R⁴ on different Ar¹ groups may together representbridging oxygen or sulphur atoms or NR⁵ or CR⁵ ₂ groups, where R⁵represents a hydrogen atom or an optionally hydroxylated, optionallyaminated, optionally alkoxylated, optionally carboxylated alkyl,oxo-alkyl, alkenyl or alkaryl group;

or groups R² and R³ may also represent hydrogen atoms or alkyl groups;

or adjacent groups R¹, R², R³ or R⁴, preferably groups at the ortho andmeta portions, together with the two intervening carbon atoms mayrepresent groups of formula ##STR1## where R⁶ represents a hydrogenatom, a hydroxyl group, an optionally alkoxylated, optionallyhydroxylated acyloxy or alkyl group or a solubilising group M; Zrepresents an oxygen or sulphur atom or a group NR⁵, CR⁷ ₂, SiR⁷ ₂ ;each R⁷ which may be the same or different, represents a hydrogen atom,an alkyl, hydroxyalkyl, carboxy, alkoxycarbonyl or carbamoyl group ortwo groups R⁷ together with the atom to which they are bound represent acarbonyl group or a 5 to 8 membered cycloalkylidene, mono- ordi-oxacycloalkylidene, mono- or di-azacycloalkylidene or mono- ordi-thiacycloalkylidene group optionally with the ring attachment carbonreplaced by a silicon atom (preferably however in any spiro structurethe ring linking atom will be bonded to no more than three heteroatoms)and R⁷ where it is other than hydrogen, is optionally substituted by agroup R⁶ ; or a salt thereof.

In the radicals of formula I, the groups Ar¹ are preferably groups offormula ##STR2## where each Y independently represents CH, or morepreferably CM, C--XM, C--Ar², C--XAr² or a nitrogen atom.

Certain of the radicals of formula I are new and they, their salts andtheir non-radical precursors (i.e. compounds of formula (Ar¹²)₃ CX⁴ or(Ar¹)₃ CX⁴ where X⁴ is a leaving group, e.g. hydrogen, hydroxyl,halogen, carboxyl, CO₂ OCO.C(Ar¹²)₃ or NNC(Ar¹²)₃) form further aspectsof the present invention.

In the inert carbon radicals of formula I, the solubilizing groups M maybe any of the solubilizing groups conventionally used in diagnostic andpharmaceutical products. Particularly preferred solubilizing groups Minclude optionally hydroxylated, optionally alkoxylated alkyl oroxo-alkyl groups and groups of formulae R⁵, COOR⁵, OCOR⁵, CHO, CN, CH₂S(O)R⁵, CONR⁵ ₂, NR⁵ COR⁵, NR⁵ ₂, SO₂ NR⁵ ₂, OR⁵, PO₃ ²⁻, SOR⁵, SO₂ R⁵,SO₃ M¹, COOM¹ (where M¹ is one equivalent of a physiologically tolerablecation, for example an alkali or alkaline earth metal cation, anammonium ion or an organic amine cation, for example a meglumine ion),--(O(CH₂)_(n))_(m) OR⁵ (where n is an integer having a value of from 1to 3 and m is an integer having a value of from 1 to 5), ##STR3## or CH₂R⁸ (where R⁸ is a hydrophilic R⁵ group) or SR¹⁰ where is a group R⁵ oran alkyl group optionally substituted by one or more, especially two orthree groups COOR⁵, OCOR⁵, CHO, CN, CONR⁵ ₂, NR⁵ COR⁵, NR⁵ ₂, SO₂ NR⁵ ₂,OR⁵, PO₃ ²⁻, SOR⁵, SO₂ R⁵, SO₃ M¹, COOM¹, or --(O(CH₂)_(n))_(m) OR⁵.

Especially preferred as solubilizing groups M are groups of formulaC(H)_(3-n) (CH₂ OH)_(n), R⁹, COR⁹, SR⁹, SOR⁹, SO₂ R⁹, CON(R⁹)₂, NR⁹ ₂,NHR⁹ and CONHR⁹ [where R⁹ may represent a group ##STR4## (although anyR⁹ group attached to a sulphur, nitrogen or oxygen atom is preferablynot hydroxylated at the α carbon)], and groups of formula SR¹² where R¹²is a group CH₂ COOR¹³, CH(COOR¹³)₂, CH₂ CONHR⁹, CH₂ CONR⁹ ₂, CR⁵(COOR¹³)₂, CH(CN)CO₂ R¹³, (CH₂)_(n) SO₃ ⁻ M¹, (CH₂)_(n) COR¹,CH(COR⁹)CH₂ COR⁹ and CH(R⁵)COR⁹ where n, M¹ and R⁵ are as earlierdefined and R¹³ is a hydrogen atom, an alkyl group or a group M¹ or R⁹.

Further especially preferred solubilising groups M or XM include groupsof formula X'C((CH₂)_(n) COOR¹³)₂ R¹⁴, X'C((CH₂)_(n) COOR¹³)₃ andX'C((CH₂)_(n) COOR¹³)R¹⁴ ₂, where R¹³ is as defined above, n is aninteger from 1 to 3, X' is an oxygen or sulphur atom, and R¹⁴ is ahydroxyalkyl group such as a group R⁹ as earlier defined.

Other examples of preferred R¹ groups include for example the followingstructures

--S--(CH₂ CH₂ O)_(n') R¹⁹ where n' is 0, 1 or 2 and R¹⁹ is hydrogen orC₁₋₄ alkyl

--S--(CH₂)_(n') --CO--R²³ where R²³ is C₁₋₄ alkyl (e.g. methyl, ethyl ort-butyl), NR₂ ²¹ or OR²¹ and R²¹ is C₁₋₄ alkyl

--COR²² where R²² is hydrogen, hydroxyl, R²³, or COOR²¹

--CH₂ O[CH₂ CH₂ O]_(n') CH₃

--CH₂ OCOR²¹ and ##STR5## where X is oxygen or sulphur.

Where M represents a group containing a moiety NR⁵ ₂, this may alsorepresent an optionally substituted nitrogen-attached 5 to 7 memberedheterocyclic ring optionally containing at least one further ringheteroatom, e.g. N or O, for example a group of formula ##STR6##

In the inert carbon radicals of formula (I), any alkyl or alkenyl moietyconveniently will contain up to 6, especially up to 4, carbon atoms andany aryl moiety will preferably contain 5 to 7 ring atoms in the or anyaromatic ring and especially preferably will comprise an aromatic ringwith 0, 1 or 2 further aromatic rings fused directly or indirectlythereto.

Preferred structures for the aryl substituents on the carbon radicalcentre include those in which at least one of such substituents carriesat least one, and preferably two, fused rings of formula ##STR7## whereX and Z are as defined before, especially rings of formulae ##STR8##where X is oxygen or sulphur and R⁷ is hydrogen or optionallyhydroxylated methyl.

Particularly preferred structures for the aryl groups Ar¹ in the inertcarbon free radicals of formula I include the following: ##STR9##wherein X is oxygen or sulphur, Y is N, CCOOR⁵, CSR⁵, CM or C--XM and M,R⁵ and Z are as earlier defined.

Particularly preferred structures include those in which CR⁷ ₂represents CH₂, C(CH₂ OH)₂ or C(CH₃)₂, X represents an oxygen or sulphuratom and those of formula ##STR10## where R¹ is a group M or XM ashereinbefore defined and M² represents a solubilising group M or a groupSCH₃, S(O)CH₃, S(O₂)CH₃, SCH₂ CH₂ N(CH₃)₂, SCH₂ COOH, SCH₂ COOCH₃, SCH₂COOCH₂ CH₃ and SC(H)_(3-n) (CH₂ OH)_(n) where n is an integer of from 1to 3.

Especially preferred groups Ar¹ include optionally substitutedbenzo[1,2-d:4,5-d']bis[1,3]dioxole, benzo[1,2-d:4,5-d']bis[1,3]dithiole,and benzo[1,2-d:4,5-d']bis[1,3]oxathiole groups.

Preferred inert carbon free radicals for use according to the inventioninclude the following: ##STR11## Especially preferred inert cation freeradicals include ##STR12## and water soluble derivatives thereof such as##STR13## (where each of R⁴², R⁴³ and R⁴⁴ are non-ionic solubilisinggroups e.g. hydroxyalkyl or alkoxyalkyl groups); ##STR14## and watersoluble derivatives thereof such as ##STR15## (where R⁴², R⁴³ and R⁴⁴are as defined above).

Inert free radicals which have relatively few transitions, e.g. lessthan 15, preferably less than 10, in their ESR spectra and radicalshaving narrow linewidth ESR transitions, e.g. up to 500 mG, preferablyless than 150 mG, especially less than 60 mG and particularly less than25 mG, are especially preferred for use as ESREMRI contrast agents. (Thelinewidths referred to are conveniently the intrinsic linewidths (fullwidth at half maximum in the absorption spectrum) at ambientconditions).

Whilst low numbers of ESR transition lines are generally preferred toobtain more effective coupling of the ESR and NMR transitions, we havefound that surprisingly good coupling, and therefore enhancement of theMR signal, may also be achieved with radicals showing a large number ofESR transitions.

Where the radicals have a multiplicity of ESR transitions, the hyperfinesplitting constant is preferably very small. In this connection radicalshaving as few as possible non-zero spin nuclei, positioned as far awayas possible from the paramagnetic centre are thus especially preferred.

Certain of the triarylmethyl free radicals of formula I are themselvesnovel and in a further aspect the present invention also provides novelinert carbon free radicals of formula I or salts thereof.

Most known triarylmethyl radicals have short relaxation times and halflives and are generally unstable, being oxygen-sensitive andparticularly susceptible to dimerization, and thus would not generallybe considered for use as contrast agents. Moreover known triaryl methylradicals are water-insoluble and are therefore generally not suited foradministration to the body. It was not therefore obvious to use triarylmethyl radicals as ESREMRI contrast agents.

The novel triarylmethyl radicals of the invention include radicals whichsurprisingly are stable at physiological pH, have long half lives (atleast one minute, and preferably at least one hour), long relaxationtimes, and exhibit surprisingly good relaxivity. Water-soluble triarylmethyl radicals are a particularly important aspect of the invention.

The triarylmethyl radicals may be coupled to further molecules forexample to lipophilic moieties such as long chain fatty acids or tomacromolecules, such as polymers, proteins, polysaccharides (e.g.dextrans), polypeptides and polyethyleneimines. The macromolecule may bea tissue-specific biomolecule such as an antibody or a backbone polymersuch as polylysine capable of carrying a number of independent radicalgroups which may itself be attached to a further macromolecule. Couplingto lipophilic molecules or substitution of the radical with lipophilicgroups is particularly useful since it may enhance the relaxivity of theradicals in certain systems such as blood. Such lipophilic andmacromolecular derivatives of the radicals of formula I and saltsthereof form a further aspect of the present invention.

The linkage of a compound of formula I to the further molecule may beeffected by any of the conventional methods such as the carbodiimidemethod, the mixed anhydride procedure of Krejcarek et al. (seeBiochemical and Biophysical Research Communications 77: 581 (1977)), thecyclic anhydride method of Hnatowich et al. (see Science 220: 613 (1983)and elsewhere), the backbone conjugation techniques of Meares et al.(see Anal. Biochem. 142: 68 (1984) and elsewhere) and Schering (seeEP-A-331616 for example) and by the use of linker molecules as describedfor example by Nycomed in WO-A-89/06979.

In view of their surprisingly beneficial properties, the noveltriarylmethyl radicals of the invention may also be used as ESR spinlabels in ESR imaging or in magnetometry.

The inert carbon free radicals may be prepared from their non-radicalprecursor compounds by conventional radical generation methods. Suitablenon-radical precursor compounds include the corresponding triarylmethanes, triaryl methyl halides and triaryl methanols, and derivatives,e.g. ethers, of the triaryl methanols.

Thus in a further aspect the invention provides a process for thepreparation of the novel triarylmethyl radicals of the invention whichcomprises subjecting a radical precursor therefor to a radicalgeneration step and optionally subsequently modifying the substitutionon the aryl moieties, e.g. by oxidation or reduction. By suchmodification for example sulphide substituents, (e.g. --SCH₃ or --SCH₂COOEt) may be oxidized to the corresponding sulphones so avoidingproblems of acidic hydrogens prior to radical formulation. Similarlylipophilic substituents (such as --SCH₂ COOEt) may be reduced tocorresponding hydrophilic substituents (e.g. --SCH₂ CH₂ OH).

Thus by way of illustration the radical-precursor can be represented byformula XXXV

    (Ar.sup.12).sub.3 CLv (Lv)                                 (XXXV)

where Lv is a group displaceable to produce a radical Formula XXXVembrace formulae such as

    (Ar.sup.12).sub.3 COH                                      (II)

    (Ar.sup.12).sub.3 CHal                                     (III)

    (Ar.sup.12).sub.3 CH                                       (IV)

    (Ar.sup.12).sub.3 CCOOH                                    (XXXI)

    (Ar.sup.12).sub.3 C.CO.O.O.CO.C(Ar.sup.12).sub.3           (XXXII)

    (Ar.sup.12).sub.3 C.NNC(Ar.sup.12).sub.3                   (XXXIII)

Where Hal represents halogen, e.g. Br or Cl).

Thus for example carbon free radicals may conveniently be prepared fromcorresponding triaryl methyl halides by reduction with a metal catalyst,such as copper, zinc or silver, or by electrolytic reaction on anelectrode or by photochemical reaction in the presence of a chlorineradical scavenger, e.g. an olefin. Alternatively, carbon free radicalsmay be prepared from the corresponding triaryl methanes by reaction witha base, e.g. in the presence of sodium hydride followed by a reactionwith an oxidant, e.g. iodine in the presence of oxygen or a quinone suchas chloranil, following for example the method described in U.S. Pat.No. 3,347,941. Another method to prepare triarylmethyl radicals is toreact triarylmethanes with other, less stable radicals such astert-butoxyl radicals. The latter radicals are generated in situ viathermolysis or photolysis of an appropriate precursor, such as aperoxide or an azo compound. A further example of a method by whichradical preparation may be effected is reaction of the correspondingtriaryl methanols in the presence of an acid to form a carbonium ionfollowed by reduction to the free radical in the presence of a suitablereducing agent, such as metal ions e.g. Cr²⁺, Fe²⁺, or byelectrochemical reduction. The carbon free radicals may also begenerated by a comproportionation reaction between cations and anions ofa corresponding radical precursor. In such a reaction an electron isexchanged between the anion and the cation, and two radicals aregenerated. Triarylmethyl radicals may thus be prepared by mixingtogether a triarylmethyl radical precursor cation with a correspondinganion. Triarylmethyl radicals may also be prepared by thermolysis orphotolysis or a corresponding dimeric triarylmethyl structure, forexample an azobistriarylmethyl or a bis (triarylmethylcarboxylic acid)peroxide. An alternative method of preparation of triarylmethyl radicalsis the electrochemical decarboxylation of a triarylmethylcarboxylate.

While radicals with long half lives in aqueous solution, for example atleast one hour, preferably ten days, more preferably fifty days andespecially preferably at least one year are clearly particularlydesirable for use in in vivo imaging, shorter lived inert free radicalsmay still be utilised in imaging (e.g. of inanimate samples) and thesemay particularly conveniently be prepared immediatelypre-administration.

The non-radical precursors may themselves be prepared by methodsconventional in the art. Thus a process for the preparation of a triarylmethyl radical precursor may comprise one or more of the followingsteps:

a) (to prepare a triarylmethanol of Formula II

    HO--C(Ar.sup.12).sub.3                                     (II)

wherein Ar¹² is as hereinbefore defined) reacting a compound of formulaXXIII

    H--Ar.sup.12                                               (XXIII)

with alkyl lithium (e.g. BuLi) and a compound of formula CO(OR")₂ (whereR" is an alkyl group, e.g. a C₁₋₉ alkyl especially ethyl);

b) (to prepare a triarylmethanol of Formula II

    HO--C(Ar.sup.12).sub.3                                     (II)

wherein Ar¹² is as hereinbefore defined) reacting an organometalliccompound comprising a metal linked Ar¹² moiety (e.g. Ar¹² Li or Ar¹²MgHal) with a compound of formula XXV, XXVI or XXVII

    R"OCOOR"                                                   (XXV)

    Ar.sup.12 COOR"                                            (XXVI)

    (Ar.sup.12).sub.2 CO                                       (XXVII)

where R" is as hereinbefore defined, especially methyl);

c) (to prepare a triarylmethanol of Formula II

    HO--C(Ar.sup.12).sub.3                                     (II)

wherein Ar¹² is as hereinbefore defined) hydrolysing a compound offormula III

    Hal-C(Ar.sup.12).sub.3                                     (II)

(where Hal and Ar¹² are as hereinbefore defined);

d) (to prepare a triarylmethanol of Formula II

    HO--C(Ar.sup.12).sub.3                                     (III)

wherein Ar¹² is as hereinbefore defined) reacting a compound of formulaXXVII with a compound of formula Hal-Ar¹² ;

e) (to prepare a triarylmethyl halide of Formula III

    HO--C(Ar.sup.12).sub.3                                     (III)

wherein Ar¹² is as hereinbefore defined) halogenating a triarylmethaneof formula IV

    HC(Ar.sup.12).sub.3                                        (IV)

(e.g. under illumination or by reaction with N-bromosuccinimide orthionyl chloride or by reaction with a tetrahalomethane, e.g. CCl₄, inthe presence of AlCl₃) or halogenating a triarylmethanol of formula II;

f) (to prepare a triarylmethane of formula IV) reacting a compound offormula XXIII with a trialkoxymethane of formula XXVIII

    (R"O).sub.3 CH                                             (XXVIII)

(where R" is as hereinbefore defined, especially methyl), e.g. in thepresence of AlCl₃ ;

g) (to prepare a triarylmethane of formula IV) hydrogenating orotherwise reducing a triarylmethyl halide of formula III or atriarylmethanol of formula II (e.g. using sodium borohydride ortrimethylsilylchloride and potassium iodide;

h) (to prepare a triarylmethane of formula IV) reacting a compound offormula XXIII with a compound of formula XXIX

    (Ar.sup.12).sub.n.sbsb.1 CHHal.sub.n.sbsb.2                (XXIX)

(wherein n₁ is 0, 1 or 2 and n₂ is 1, 2 or 3 and n₁ +n₂ is 3) ,e.g. inthe presence of AlCl₃ ;

i) (to prepare a triarylmethane of formula IV) reacting a compound offormula XXX

    (Ar.sup.12).sub.2 CHLv                                     (XXX)

(where Lv is a leaving group, e.g. OTs) with an organometallic compoundcomprising a metal linked Ar¹² moiety (e.g. Ar¹² CuLi);

j) (to prepare a triarylacetic acid of formula XXXI

    (Ar.sup.12).sub.3 CCOOH                                    (XXXI)

(where Ar¹² is as hereinbefore defined) reacting a triarylmethyl halideof formula III with carbon monoxide (e.g. in the presence of Co₂ (CO)₈)on a triarylmethyl organometallic compound with carbon dioxide;

k) (to prepare a compound of formula XXXII

    (Ar.sup.12).sub.3 CCOOOCOC(Ar.sup.12).sub.3                (XXXII)

(where Ar¹² is as hereinbefore defined) reacting a triarylacetic acidwith thionyl chloride and a peroxide, e.g. H₂ O₂ ;

l) (to prepare a compound of formula XXXIII

    (Ar.sup.12).sub.3 CN═NC(Ar.sup.12).sub.3               (XXXIII)

(where Ar¹² is as hereinbefore defined) oxidizing a triarylmethylaminehalide of formula XXXIV

    (Ar.sup.12).sub.3 CNHHal                                   (XXXIV)

e.g. with silveroxide;

m) reacting a triarylmethyl radical precursor to modify the substitutionon one or more of the aryl moieties.

For process step (b), the starting ketone of formula XXVII may beprepared by oxidation, e.g. with CrO₃, of the corresponding alcohol(Ar¹²)₂ CHOH (itself preparable by reaction of the monoaldehyde Ar¹² CHOwith an Ar¹² containing organometallic, e.g. Ar¹² Li or Ar¹² MgHal), orby reaction of such an organometallic with the corresponding carboxylicacid Ar¹² COOH, or by reaction of the acid chloride Ar¹² COCl with Ar¹²H, e.g. in the presence of AlCl₃.

For process step (d), the starting material of formula XXXIV may beprepared by reaction of a corresponding triarylmethyl carbanion with NH₂Cl and subsequently with bromate.

The reduction of step (g) may be effected using borane or LiAlH₄ andAlCl₃.

Triaryl methyl halides may be prepared following the proceduresdescribed by Dunnebacke et al. in Chem. Ber. 122:533-535 (1989).

In synthesising substituted triaryl methyl radicals, the substituentsmay be introduced onto individual Ar¹² groups before they are trimerizedto form the triaryl radical precursor compounds, or they may beintroduced directly onto the triaryl precursor compound or the actualradical itself. It is also possible to effect the substitution andtrimerization steps simultaneously in a "one-pot" reaction.

The Ar¹² groups may be prepared by following reaction schemes such asthose suggested below ##STR16## (wherein R⁷ ' is a hydrogen atom or agroup R⁷ as hereinbefore defined, optionally protected by a protectinggroup). ##STR17## (wherein R^(7') is as defined above) ##STR18## Tointroduce substituents onto the Ar¹² groups such as solubilising groupsM for example, reaction schemes such as the following may be used##STR19## wherein in each of schemes (i) to (xxiv) set out above R¹ ' toR⁴ ' are optionally protected groups R¹ to R⁴ and R⁵ is as hereinbeforedefined. Particularly preferably, R¹ ' and R² ' and R³ ' and R⁴ ' mayrepresent ring-forming groups --X--CR^(7') ₂ --X--, e.g. OC(CH₃)₂ O--.

Similar procedures may be used for the introduction of substitutentsonto heterocyclic Ar¹² groups.

The following are examples of schemes for "one-pot" synthesis of triarylmethyl radical precursors. ##STR20##

As indicated above, a particularly interesting group of radicals for useaccording to the invention includes compounds of Formula .C(Ar¹²)₃,where one, two or three Ar¹² groups comprises a central 5-6 memberedcarbocyclic or heterocyclic aromatic ring bearing two five-memberedfused rings, each said fused ring comprising two ring heteroatomsselected from oxygen and sulphur.

The "monomer" and "dimer" compounds, having this structure areparticularly useful for the preparation of the radical precursors andthus in a further aspect the invention provides tricylic compoundcomprising a central 5-6 membered carbocyclic or heterocyclic aromaticring bearing two five-membered fused rings, each said fused ringcomprising two ring heteroatoms selected from oxygen and suphur.Particularly preferred embodiments of such compounds are the compoundsof formula XL ##STR21## (where X and R⁷ are as hereinbefore defined, Y¹is a group CH, N, CCOOR⁵, CSR⁵, CM or CXM, R⁵ and M are as defined inclaim 6 and R⁴⁰ is a hydrogen atom, or a optionally substitutedhydroxyl, methyl or formyl group or group ##STR22## where Z'" is CHOH,C═O or CHHal and Hal is a halogen atom), or a salt thereof.

Particularly preferred compounds of formula XL include those whereineach X is oxygen, each R⁷ is optionally hydroxylated methyl and Y¹ isother than N.

The invention also provides, in another aspect, process for thepreparation of a compound of formula XL, said process comprisingcondensing a compound of formula XLI ##STR23## (wherein R^(40') and Y"are groups R⁴⁰ or Y¹ as defined in claim 23 or protected such groups,and X is as defined in claim 23) with a compound of formula (R^(7'))₂ CX(where R^(7') is a group R⁷ as defined in claim 23 or a protected R⁷group) under oxidizing conditions and if necessary removing anyprotecting groups, optionally after reduction (e.g. with Fe/HCl) of acompound of formula XLII ##STR24## to yield the starting material offormula XLI.

For use in ESREMRI, the inert carbon free radicals are convenientlyformulated into contrast media together with conventional pharmaceuticalcarriers or excipients. Contrast media manufactured or used according tothis invention may contain, besides the inert free radicals (or thenon-radical precursor where radical formation is to be effectedimmediately before administration), formulation aids such as areconventional for therapeutic and diagnostic compositions in human orveterinary medicine. Thus the media may for example include solubilizingagents, emulsifiers, viscosity enhancers, buffers, etc. The media may bein forms suitable for parenteral (e.g. intravenous) or enteral (e.g.oral) application, for example for application directly into bodycavities having external voidance ducts (such as the gastrointestinaltract, the bladder and the uterus), or for injection or infusion intothe cardiovascular system. However solutions, suspensions anddispersions in physiological tolerable media will generally bepreferred.

Free radicals which are relatively unstable or insoluble in the sampleenvironment may be encapsulated, e.g. in gastric juice resistantcapsules containing a medium in which they are stable. Alternatively,the radical may be presented as an encapsulated freeze dried powder in asoluble capsule. Such formulations might conveniently be dissolvedshortly before in vivo use.

For use in in vivo diagnostic imaging, the medium, which preferably willbe substantially isotonic, may conveniently be administered at aconcentration sufficient to yield a 1 micromolar to 10 mM concentrationof the free radical in the imaging zone; however the preciseconcentration and dosage will of course depend upon a range of factorssuch as toxicity, the organ targetting ability of the contrast agent,and the administration route. The optimum concentration for the freeradical represents a balance between various factors. In general,optimum concentrations would in most cases lie in the range 0.1 to 100mM, especially 0.2 to 10 mM, more especially 0.5 to 5 mM. Compositionsfor intravenous administration would preferably contain the free radicalin concentrations of 10 to 1000 mM especially 50 to 500 mM. For ionicmaterials, the concentration will particularly preferably be in therange 50 to 200 mM, especially 130 to 170 mM and for non-ionic materials200 to 400 mM, especially 290 to 330 mM. For imaging of the urinarytract or the renal or biliary system however, compositions may perhapsbe used having concentrations of for example 10 to 100 mM for ionic or20 to 200 mM for non-ionic materials. Moreover for bolus injection theconcentration may conveniently be 0.1 to 100 mM, preferably 5 to 25 mM,especially preferably 6 to 15 mM.

BRIEF DESCRIPTION OF DRAWING

The accompanying drawing, FIG. 1, shows a magnetic resonance imageproduced according to the invention.

Specifically, there is shown a coronal slice through a rat followingperoral administration of a contrast medium containingtris(2,2,6,6-tetramethyl sodium-8-carboxylatemethylthiobenzo[1,2-d:4,5-d']bis(1,3)dioxole)methyl (the radical ofExample 11). The gastrointestinal tract can be seen very clearly

In FIG. 1:

1. indicates the stomach;

2. indicates the intestines;

3. indicates the head end of the rat;

4. indicates the tail end of the rat;

5. indicates the right hand side of the rat;

6. indicates the left hand side of the rat.

The image was acquired under the following conditions:

a) TR=0.5 sec, UHF Irradiation Time=0.38 sec. 256 excitations (256×256matrix). Slice thickness 1 cm. Field of view 25 cm.90° flip angle (SR).Single echo (gradient). TE=30 ms. Single slice. 1. Average.

b) The instrumental parameters were:

Proton frequency 417 kHz (H=100 G) UHF frequency=274 MHz. TheUHF-resonator had a very low loaded Q≦10 (200 g rat), and a volume ofapproximately 1 L (diameter 10 cm). The applied UHF power was ≦30 W ofwhich only a small fraction was deposited in the animal (<1/10). Theproton coil had a diameter of 126 cm and thus a very low filling factorwhen loaded with a rat (5 cm). The Q factor of this coil was high(>1000), but loaded with both UHF-resonator and animal decreased tobelow 500.

c) The signal/noise (S/N) ratio was approximately 100.

The perorally applied volume of contrast medium was approxmiately 5 mland the concentration of radical was less than 0.5 mM.

In the unenhanced image, where no contrast medium was administratered,the S/N ratio was -3 resulting in an image where no details could bedistinguished from the background noise.

The present invention will now be further illustrated by the followingnon-limiting Examples (percentages, parts and ratios are by weight andtemperatures are in degrees Celsius unless otherwise stated).

EXAMPLE 1 2,5-Dimercapto-1,4-dihydroxybenzene

Ammonia was condensed (ca 200 ml) into 150 ml of dry diethylether in a3-necked flask, with external cooling. Then 9.0 g (0.0256 mole) of2,5-dibenzylmercapto-p-benzoquinone was dissolved into the liquid.Sodium (5.9 g, 0.256 mole) cut into fine pieces was added portionwisewith efficient stirring. After stirring for an additional 2.5 hours,abs. ethanol (20 ml) was added and the ammonia was evaporated. Water(170 ml) was added to the reaction product and it was extracted with2×30 ml of ether. The aqueous phase was then acidified to pH 1-2, withconc. hydrochloric acid, and extracted with 3×80 ml of ether. The etherextracts were collected, dried (Na₂ SO₄), the solvent evaporated leavinga fluffy light brown glistening residue, 4.3 g (90%).

MS (Silated Product): M/e 462 (42% M⁺) 447 (5% M⁺ -15)

EXAMPLE 2 2,2,6,6-Tetramethylbenzo[1.2-d:4,5-d']bis(1,3)dithiole##STR25##

1,3,5,7-Tetrathia-S-indacene-2,6-dione (4.0 g, 0.016 mole, preparedaccording to Larsen and Bechgaard J. Org Chem 52: 3287 (1987)) wassuspended in 60 ml of a 1M solution of sodium methoxide in methanol.Stirring was maintained for 1/2 hour at ambient temp. until a clearsolution was formed. The reaction mixture was then evaporated to drynessand the residue acidified with 5N hydrochloric acid to pH 1. The aqueousphase was extracted with 3×70 ml of methylene chloride. The organicphases were dried (Na₂ SO₄), the solvent evaporated leaving a light tancoloured crystalline residue. This was suspended in 50 ml of drytoluene, and 3 ml of acetone and 2.5 ml of fluoroboric acid etherate(HBF₄. Et₂ O) were added. The mixture was stirred at ambient temperaturefor 5 hours then refluxed over night. The reaction mixture was thenpoured into 100 ml of cold saturated sodium hydrogen carbonate solution.The phases were separated and the organic phase was washed with 30 ml ofwater. The aqueous phases were back-extracted with 40 ml of methylenechloride. The organic phases were collected, dried (Na₂ SO₄) and thesolvent evaporated leaving a light yellow cryst. residue, 4.1 g (92%).

IR(film): 2960,2920 CM⁻¹,

1H-NMR (CDCl₃) δ: 1.88 (CH₃ 12H), 7.02 (arom H, 2H) ppm

MS: m/e 286 (14% M⁺)

EXAMPLE 3 Tris(benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR26##

3.2 g Benzo[1,2-d:4,5-d']bis(1,3)dioxole prepared according to F.Dallacker et al. Liebigs Ann. Chem. 725, 99-105 (1969) (0.019 mole) wasdissolved in 100 ml dry ether under Argon. After cooling in ice-acetoneto -15° C., 10 ml 2.5M butyllithium in hexanes (Aldrich) was added froma syringe. The cooling bath was removed and the mixture was stirred for2 hours. 0.8 ml diethylcarbonate (0.0068 mole) was added with a slightincrease in temperature and color change to yellow-brown. The mixturewas stirred at room temperature overnight and then poured over 150 mlice-water and extracted with 3×75 ml CH₂ Cl₂. The organic phase waswashed with 100 ml water, dried over MgSO₄ and evaporated to dryness toyield 2.96 g (88%) m; 125° C. (unsharp).

¹ H-NMR (CDCl₃) δ: 5.75 (CH₂, 12H); 6.25 (Arom H, 3H) ppm

MS: m/e 524 (100% M⁺)

The corresponding radical showed a linewidth of 500 mG in its ESRspectrum and an Overhauser enhancement of 8 at 5 hr UHF power.

EXAMPLE 4 1,2,4,5-Tetrahydroxybenzene[1,2-d:4,5-d']bis(1,3)dioxole

14 g 2.5-dihydroxy-1,4-benzoquinone (0.10 mole) was suspended in 100 ml96% ethanol. 0.1 g 10% Pd on C was added under N₂ and reduced at 40 Psigin a Parr apparatus (in the usual manner) until 0.10 mole H₂ wasabsorbed.

The dark reaction mixture was filtered to remove the catalyst andevaporated to dryness to afford the product in quantitative yield.

EXAMPLE 5 2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole##STR27##

18.6 g of the 1,2,4,5-tetrahydroxybenzene prepared according to Example4 (0.13 mole) and 70 ml acetone (58.6 g, 1.0 mole) was dissolved in 1 ltetrahydrofuran. 168 g P₂ O₅ (1.18 mole) was added to the vigorouslystirred mixture in portions as fast as possible. The mixture was heatedto reflux for 4 hours. After cooling to room temperature the solids werefiltered with suction and washed with 0.5 L ether. The combinedfiltrates were treated with 10 g K₂ CO₃ and stirred 1 hour, filtered andevaporated to dryness yielding a yellow-brown oily solid. The productwas triturated with petroleum ether, decanted and evaporated to yield13.8 g of the title compound (48%) as white-yellow crystals, mp=122° C.,which can be recrystalized from a small amount of petroleum ether.

¹ H NMR (CDCl₃) δ: 1.65 (CH₃, 12H); 6.75 (Arom H, 2H) ppm

¹³ C NMR δ: 25.49 (CH₃); 92.75 (Arom CH); 117.81 (CMe₂); 140.43 (Arom C)ppm

MS: m/e 222 (90% M⁺), 207 (100%, M⁺ -15)

EXAMPLE 63-Methylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole##STR28##

1.1 g of 2,2,6,6,-tetramethylbenzo(1,2-d:4,5-d']bis(1,3)dioxole preparedaccording to Example 5 (0.005 mole) was dissolved in 25 ml dry etherunder argon and treated with 2.2 ml 2.5M butyllithium in hexane, at roomtemperature. After 1 hour 0.52 g dimethyldisulfide (0.0055 mole) wasadded and the mixture stirred overnight at room temp. The reactionmixture was then poured into 50 ml ice-water. The phases were separatedand the water phase extracted with 50 ml ether. The combined organicphase was washed with 50 ml 2M NaOH, dried over MgSO₄ and evaporated toyield 1.1 g (82%) as white crystals, mp=108° C., which can berecrystallized from a small amount of methanol.

¹ H NMR (CDCl₃) δ: 1.67 (CH₃ ; 12H); 2.45 (--SCH₂, 3H) 6.26 (Arom CH,1H)

EXAMPLE 7Tris(8-Methylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methanol##STR29##

6.2 g3-methylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)-dioxoleprepared according to Example 6 (0.0235 mole) was dissolved in 150 mldry ether under argon. The solution was cooled in an ice-methanol bath,while 10 ml 2.5M butyllithium in hexane (0.025 mole) was added and thenleft with stirring at room temperature for one hour. 0.95 mldiethylcarbonate (0.0078 mole) was added.

After 18 hours the reaction mixture was poured over 200 ml ice-water andthe product extracted with 3×75 ml CH₂ Cl₂. The organic phase was washedwith 100 ml H₂ O, dried over MgSO₄ and evaporated to dryness, yieldingca 5 g yellow solid. The product was triturated with a little coldpetroleum ether and filtered to yield 2.1 g of the title compound (32%)as yellow crystals, mp>260° C.

¹ H NMR (CDCl₃) δ: 1.51 (CH₃, 36H); 2.40 (SCH₃, 9H); 4.20 (OH,1H) ppm

¹³ C-NMR δ: 17.28; 25.48; 72.56; 99.87, 111.97 138.71; 140.97.

MS: m/e 830 (80% M⁺), 714 (100% M⁺ -116)

EXAMPLE 8Tris(8-methylthio-2,2,6,6-tetramethylbenzo[1,2-d:4.5-d']-bis(1,3)dioxole)methyl##STR30##

250 mgTris-(3-methylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methanol(0.3 mmol, Example 7) was dissolved in 50 ml dry THF (Al₂ O₃, super I,basic) under Argon. 0.5 g CrCl₂ and then 0.5 ml BF₃ etherate was addedto the vigorously stirred mixture. After 15 minutes the reaction mixturewas poured over 50 ml 4M NaOH. The organic phase was separated andfiltered through a short column of SiO₂ and eluted with dry ether. Thedark violet solution was evaporated to dryness yielding 176 mg (71%) ofthe title compound as a black powder. A solution of this material intetrahydrofuran was shown to contain 41% radical according to the methodof Evans (J. Chem. Soc. 2003 (1959)).

MS: m/e 814 (60% M⁺ -1)

EXAMPLE 9Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methanol##STR31##

2.25 g (0.010 mole) of the benzobisdioxole of Example 5 in 50 mltetrahydrofuran (THF, HPLC-grade) was cooled to -80° in an dryice-acetone bath. 4.4 ml (1.1 eqv) 2.5M n-butyl lithium was added andthe mixture allowed to come to ambient temperature. After about 15minutes 0.35 g of sulphur (S₈) was added in one portion. After about 20minutes the sulphur had reacted and the brownish solution was cooled to-80° C. and treated with 4.4 mL 2.5M n-butyl lithium. The cooling bathwas removed and the temperature allowed to rise again to ambienttemperature. After about 20 minutes a cloudy suspension was obtained.0.4 mL diethylcarbonate was added.

After 1 hour, 5.5 ml (0.05 mole) of chloroacetic acid ethylester wasadded in one portion (slight heat formation). The reaction mixturebecome very dark and homogeneous. TLC in CHCl₃ showed that a "trimer"was formed along with dimeric ketones (and other products). Afteranother 1/2 hour the reaction mixture was poured into 200 mL ice-waterand extracted with 3×75 mL diethyl ether. The organic phase was washedwith 2×50 mL H₂ O, dried over MgSO₄ and evaporated to dryness yieldingan orange oil it was separated on silica with CHCl₃ -diethyl ether aseluent.

Evaporation of the solvent yielded 1.46 g orange oil (very viscous)yield: 42%. The product was verified using ¹ H NMR, ¹³ C NMR and massspectrometry.

¹ HNMR (CDCl₃) δ: 1.22 (t) (CH₃,9H); 1.50 (CH₃,36H), 3.57 (CH₂,6H); 4.1(CH₂,6H) ppm

¹³ CNMR δ: 14.10; 25.44; 35.49; 61.22; 96.64; 112.45, 117.77, 138.67,141.25, 169.016 ppm

MS m/e 1407 (10%, M+1), 1031 (30% M⁺ -15)

EXAMPLE 10Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methyl##STR32##

250 mg oftris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methanolprepared according to Example 9 was dissolved in about 100 mL THF(HPLC-grade) and placed in a 250 mL separating funnel. A rapid stream ofargon was bubbled through the solution. 200 mg CrCl₂ was added followedby 0.4 mL BF₃ -diethylether. After 5 minutes 75 mL diethylether wasadded and then the mixture was extracted with 2×75 ml H₂ O and 1×75 ml2M NaOH. The dark organic phase was filtered through 5 cm SiO₂, elutedwith diethylether and evaporated to dryness in vacuo affording ablack-brown oil that slowly solidified on addition of 5 ml methanol 177mg black crystals were obtained, and washed with petroleum ether.Radical content: 60% (NMR--Evans method) ESR 0.2 mM in Toluene: 7 linesA_(CH2) : 66 Milli Gauss linewidth: 33 Milli Gauss

EXAMPLE 11 Tris(2,2,6,6-tetramethylsodium-8-carboxylatemethylthiobenzo[1,2-d:4,5-d']bis(1,3)dioxole)methyl##STR33##

70 mg oftris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methylprepared according to Example 10 in 2 mL methanol, 120 μL NaOH/H₂ O(0.019 g NaOH) were sonicated for 0.5 hr. A test sample (few drops) wasdiluted in H₂ O and diethylether was added. No color appeared in theetheric phase. The hydrolysis mixture was evaporated to dryness yielding53 mg of the title product.

EXAMPLE 12Tris(8-methoxycarbonylmethylthio-2,2,6,6,-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methanol##STR34##

11.38 g of the benzobisdioxole of Example 5 (0.051 mole) was dissolvedin 250 ml HPLC grade tetrahydrofuran under argon and cooled to -45° C.in dry ice. 26.2 mL n-butyl lithium (0.055 mole) 2.1M, was added from asyringe over about 1 minute. The temperature rose to -30° C., thecooling bath was removed and the mixture was left with stirring for 30min. It was cooled to -30° and 1.75 g S₈ was added in one portion. Thecooling bath was removed and after 35 minutes the temperature had risento 0° C. and all the sulphur had reacted. The mixture was cooled to -40°and 26.2 ml n-butyl lithium was added in one portion. The cooling bathwas removed and a slightly colored suspension was formed just above 0°C. After 1 hour the temperature has risen to 15° C. and a whitesuspension had formed, which was then cooled to -20° C. and 2 mLdiethylcarbonate was added. The mixture changed color from yellowthrough green to brown and the cooling bath was removed. After 1 hourthe temperature had risen to -20° C., was again cooled to -10° C. and 10mL chloro-acetic acid methyl ether was added (exothermic). The coolingbath was removed and the mixture become homogeneous and very dark. After1/2 hour the reaction mixture was poured into ice-water (500 ml) and 20mL acetic acid added. 300 mL diethyl ether was added and the phases wereseparated. The water phase was extracted with additional diethyl ether.The organic phase was stirred for 15 minutes with 10 g K₂ CO₃(anhydrous), decanted and washed with two lots of 200 mL H₂ O, driedover MgSO₄ and evaporated. It was then separated on a "TLC-SiO₂ "-columnwith CHCl₃ /CH₂ Cl₂ /diethylether. Fraction 3 (the diethylether-phase)contained 9.6 g of the product (57%). It was crystallized fromcyclohexane to yield 2.5 g yellow crystalline powder.

¹ H NMR (CDCl₃) δ: 1.485 (CH₃, 36H); 3.65 (OCH₃ ; 9H); 3.54 (CH₂ 6H) ppm

¹³ C NMR: 25.25, 35.31, 52.23; 72.41; 96.43, 112.42, 117.71, 138.57;141.22; 169.43.

MS M/e 1004 (70% M⁺); 988 (50% M⁺ -16)

EXAMPLE 13Tris(8-methoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methyl##STR35##

1.0 g oftris(8-methoxycarbonylmethylthio-2,2,6,6,-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole)methanolprepared according to Example 12 was dissolved in 150 mL THF(HPLC-grade) in a separating funnel. 1.0 g CrCl₂ (anhydrous) was addedand a rapid stream of argon was passed through the solution. 2 mL BF₃/diethylether was added followed by diethylether after 10 min. Inorganicsalts were extracted with H₂ O and 2M NaOH. The organic phase wasfiltered through a short column of SiO₂ and exaporated to a brown-blackoil. It was taken up in about 20 mL methanol and precipitated with ahalf volume of H₂ O, filtered and dried in vacuum to yield 0.78 g of ablack brown powder.

EXAMPLE 14 Tris(8-mercapto-2,26,6-tetramethylbenzo[1,2-d:4,5-d:4,5-d']bis(1,3)dioxole)methanol##STR36##

4.5 g of the benzobisdioxole of Example 5 were dissolved (under N₂) inabout 100 ml THF (HPLC-grade) and cooled to -78° C. in dry-ice acetonebath, 85 ml 2.5 m butyllithium (BuLi) (in hexane) was added. A transientcolor change to red was observed with the first drops of BuLi, butalmost immediately the color changed to very pale yellow. Thecooling-bath was removed. After 20 minutes the reaction mixture wastemporarily cooled and 0.64 g S₈ (powder) was added in one portion. Thecooling bath was removed and the color changed to light yellow as theparticles of sulphur reacted just below 0° C. The reaction mixture wasleft to stand with stirring at ambient temperature for an additional 30minutes. After cooling to -78° C., 2.5 ml BuLi 2.5 m) was added. Afterstirring for 1 hour at room temperature a white, thin, slurry hadformed. It was cooled to 78° C. and 0.81 ml diethylcarbonate was addedslowly. The mixture was left to stir at ambient temperature and thewhite suspension thickened and changed colour from yellow to brown.

After 1.5 hours the reaction mixture was poured into 100 ml diethyletherwith about 30 g NaH₂ PO₄ saturated with N₂. The phases were separatedand the H₂ O-phase was extracted once with 100 ml diethylether. Thecombined organic phase was washed once with H₂ O with about 15 g NaH₂PO₄, dried over MgSO₄, filtered and evaporated in vacuo to yield 5.0 gvoluminous semi solid. The product was taken up in approximately 20 mldiethylether and slowly precipitated with heptane, filtered off anddried in vac. to afford 4.55 g yellow powder. It was purified onTLC-silica 60M (Merck). 1 g material was dissolved in 20 ml diethyletherapplied to a flash column (400 ml SiO₂ in diethylether-heptane (7:3) andeluted with diethylether until the first yellow band appeared, yielding0.20 g of a nearly colorless yellow crystalline solid.

¹ H NMR (CDCl₃) δ: 1.49 (CH₃), 3.25 (SH), 4.10 (OH)

¹³ C NMR δ: 25.48, 72.33, 93.55, 110.66, 117.51, 138.26 and 138.54.

EXAMPLE 15Tris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR37##

Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(1.26 g, 1.62 mmol (prepared by reaction oftris(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxol-4-yl)methanol(See Example 44) with nBuLi in DMF)) was dissolved in dry MeOH (80 mL).To this solution was added MnO₂ (18.9 g, 217 mmol), NaCN (1.26 g, 25.7mmol) and acetic acid (HOAc) (1.26 mL). The reaction mixture was heatedto 65° C. for 40 h and was then filtered through Celite and the filtratewas evaporated to dryness. The residue was partitioned between CH₂ Cl₂(100 mL) and water (40 mL). The organic phase was washed with another2×30 mL of water, the organic phase was separated, dried (Na₂ SO₄) andthe solvent was evaporated to yield a yellow to brown residue, which wasfurther pumped to dryness. The residual foam was chromatographed on acolumn packed with SiO₂, eluting with CH₂ Cl₂ /Et₂ O (4:1). Thefractions containing pure product were collected and the solvent wasevaporated to yield 1.1 g (77%) of puretris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol.

¹ H NMR (CDCl₃, 300 MHz) δ: 1.44 (CH₃, 36H, s), 3.78 (OCH₃, 9H, s), 4.24(OH, 1H, s).

¹³ C NMR (CDCl₃, 75 MHz) δ: 163.4 (C═O), 140.5 139.2 (aromatic C--O),118.3 (alifatic O--C--O), 115.0 (quart. C-subst. aromatic), 99.1 (quart.p-C-subst. aromatic), 72.6 (quart. alifatic C--OH), 51.9 (OCH₃), 25.5(CH₃).

MS (Thermospray): M⁺ +23 (Na) 888, 889.

EXAMPLE 16Tris(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR38##

The ester of Example 15,tris(8-methoxycarbonyl-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(0.30 g, 0.34 mmol) was dissolved in MeOH (10 mL), and NaOH (0.041 g,1.02 mmol) dissolved in MeOH/H₂ O (2.32M NaOH solution) was added untilpH reached 7. In total 0.44 mL of the basic solution was used. The MeOHwas evaporated in vacuum due to solubility problems and THF (3.5 mL) wasadded. The reaction mixture cleared with this treatment. After 12 h thereaction mixture was turbid and a precipitate had formed. Thisprecipitate dissolved with the addition of water (10 mL). The THF wasevaporated under reduced pressure and water (10 mL) was added and theaqueous phase was extracted with ether (10 mL). The organic phase wasseparated and the aqueous phase was acidified (pH 3.5) with 2M HCl. Ayellow precipitate was formed and the aqueous phase was extracted withether (3×20 mL) and CH₂ Cl₂ (30 mL). The organic phases were collected,dried (Na₂ SO₄) and the solvent was evaporated to yield the producttris(8-carboxy-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanolas a slightly tanned residue (0.25 g, 87%). The product contained asmall impurity (appreciated to about 2% at the same extinction)according to HPLC (C18, ion pair (tetrabutyl-ammonium acetate)chromatography, CH₃ CN:H₂ O) with UV (254 nm) detection.

¹ H NMR (D₂ O, 300 MHz) δ: 1.26 (CH₃, 36H, s).

¹³ C NMR (D₂ O, 300 MHz) δ: 169.6 (C═O), 138.9 138.8 (aromatic C--O),118.2 (alifatic O--C--O), 111.9 (quart. C-subst. aromatic), 105.9(quart. p-C-subst. aromatic), 72.1 (quart. alifatic C--OH), 24.6 (CH₃).

IR (KBr, cm-1): 3450 (OH-stretching broad), 1670 (C═O stretching s).

EXAMPLE 17Tris(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane##STR39##

Trimethylsilyl chloride (68.1 mL, 539 mmol) and sodium iodide (81.0 g,540 mmol) were mixed in acetonitrile (500 mL), andtris(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(62.4 g, 90.2 mmol, Example 44) and was added with efficient stirring atroom temperature. The reaction flask was surrounded with aluminum foilto prevent light to enter. After stirring for 24 h, the reaction mixturewas poured into 2 L of a Na₂ S₂ O₃ solution (70 g of Na₂ S₂ O₃ ×5 H₂ Oin 2 L of water). A yellow precipitate was formed, filtered off and wasleft to dry on the filter under suction (2 h). The product wastriturated with i-PrOH twice, filtered and washed with cold diisopropylether (15 mL) to yield 54.1 g (88%) of the producttris(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane.

¹ H NMR (CDCl₃, 300 MHz) δ: 1.47 (CH₃, 36H, s), 5.42 (CH, 1H, q, J=0.37Hz), 6.20 (aromatic H, 3H, d, J=0.37 Hz).

¹³ C NMR (CDCl₃, 75 MHz) δ: 139.5 139.8 (aromatic C--O), 116.7 (alifaticO--C--O), 107.6 (quart. aromatic), 90.7 (aromatic C--H), 30.7 (C--H),25.3 (CH₃).

MS (EI): M⁺ -16 (676, 100%), M⁺ -15 (678, 40%), 338.5 (70%).

EXAMPLE 18Tris(8-carboxyl-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methaneandbis(8-carboxyl-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)-(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane##STR40##

Tris(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane(1.65 g, 0.244 mmol, Example 17) was dissolved in dry diethyl ether (150mL). n-BuLi (5.86 mL, 2.5M in toluene, 1.465 mmol) was added in twoportions (2/3 and 1/3), and the temperature of the mixture was raised to40° C. (the ether refluxed). After maintaining this temp. for 15-20 min,the mixture was poured onto CO₂ (s), and left overnight. Water (90 mL)was added to dissolve the solid residue. The aqueous phase was washedwith ether (50 mL). The aqueous phase was then acidified with 2M HCl topH 1-2, and the tan coloured precipitate which formed was filtered off,washed with of water (7 mL) and dried. RP-TLC (SiO₂ RP18: glassplates)in MeOH:H₂ O (4:1) showed mainly two spots, (diacid and triacid withRf=0.51 and 0.81, respectively). The producttris(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanewas not separated from the mixture (1.43+0.10=1.53 g (raw material ofacids)) but was used without further purification in esterification oramidation reactions. The products of these reactions can be separated bychromatography.

EXAMPLE 19Tris(8-methoxycarbonyl-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methaneandbis(8-methoxycarbonyl-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)-(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane##STR41##

A mixture of the acidstris(8-carboxy-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methaneandbis(8-carboxy-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)-dioxole-4-yl)-(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane(3.0 g, 0.36 mmol, Example 18) were dissolved in dry DMF (70 mL) and Cs₂CO₃ (9.8 g, 30 mmol) was added. The mixture was heated to 70° C. for 1.5h and was then cooled to room temperature and CH₃ I (6.74 mL, 108 mmol)was added with efficient stirring at 35° C. for 40 h, and the reactionmixture was filtered and the solvent (DMF) evaporated at reducedpressure. The residue was partitioned between CH₂ Cl₂ (200 mL) and water(70 mL). The organic phase was extracted with another portion of water(70 mL). The aqueous phases were extracted back with of CH₂ Cl₂ (70 mL).The organic phases were extracted with a solution of saturated NaHCO₃,dried (Na₂ SO₄) and the solvent evaporated, leaving a light browncrystalline residue (3.05 g), which was chromatographed on a semipreparative reversed phase column (30 cm i.d., packed with 10 μmKromasil, C8), eluting with CN:H₂ O (75:25).

Yield oftris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane1.70 g (55%).

¹ H NMR (CDCl₃, 300 MHz) δ: 1.53 (s, CH₃, 36H, 3.87 (s, OCH₃, 9H), 5.42(s, CH, 1H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 163.8 (C═O) 140.1, 140.0 (aromatic C--O),118.4 (aliphatic O--C--O), 110.3 (quart. arom. C), 98.5 (p-substitutedquart. aromatic), 51.8 (OCH₃), 31.3 (C--H), 25.5 (CH₃).

MS (Thermospray: M⁺ +23 (Na) 873.

Yield ofbis(8-methoxycarbonyl-2,2,6,6,-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)-(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane=0.60g (20%).

¹ H NMR (CDCl₃, 300 MHz) δ: 1.47 (s, CH₃, 12H, 1.53 (s, CH₃, 24H), 3.87(s, OCH₃, 6H) 5.42 (s, CH, 1H), 6.21 (s, aromatic H, 1H).

Ms (Thermospray): M⁺ +23 (Na) 815.

EXAMPLE 20Tris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxole-4-yl)methaneandbis(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)-dioxole-4-yl)-(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxole-4-yl)methane##STR42##

Tris(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane(3.00 g, 4.40 mmol (Example 17)) was dissolved in ether (100 mL) andn-BuLi (10.8 mL, 27.0 mmol) was added. The mixture was refluxed for 20min, and after cooling to room temperature dimethylcarbonate (5.60 mL,67.0 mmol) was added. The mixture turned dark brown, and the reactionmixture was stirred over night at room temperature. Water (40 mL) wasadded and the phases were separated. The aqueous phase was extractedwith another portion of ether (50 mL). The organic phases were pooled,dried and filtered, and the solvent evaporated leaving a semisolid brownresidue. This was chromatographed on a SiO₂ column (0.040-0.063 mm),eluting first with petroleum-ether/ether (1:4) and then with ethylacetate (EtOAc). The diesterbis(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane(1.27 g, 33.1%) and the triestertris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane(0.37 g, 11.0%) were isolated. For spectroscopic data see Example 19.

EXAMPLE 21Tris(8-ethoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane##STR43##

Tris(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane(1.35 g, 2.0 mmol (Example 17)) was dissolved in dry THF (400 mL) underN₂, and the temp was lowered to -40° C. and n-BuLi (4.86 mL, 12.2 mmol)was added and the temperature was allowed to rise gradually to 0° C. Themixture was cooled to -60° C., and a solution of ethylchloroformate(4.0, 36.7 mmol) in THF (50 mL) was added. The reaction mixture was leftovernight and worked up as described under Example 20 above. Thechromatography gave (0.41 g, 24%) oftris(8-ethoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane.

¹ H NMR (CDCl₃, 300 MHz) δ: 1.35 (t, CH₃, 9H), 1.52 (s, CH₃, 36H), 4.34(q, _(CH2), 6H), 5.41 (s, CH, 1H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 163.4 (C═O), 140.1, 140.0 (aromatic C--O),118.3 (aliphatic O--C--O), 110.2 (quart. aromatic C), 98.8 (quart.C-substituted aromatic), 60.7 (CH₂), 31.3 (C--H), 25.5 (CH₃), 14.2(CH₃).

EXAMPLE 22Tris(8-methylcarbonyloxymethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol##STR44##

Acetic anhydride (AcO)₂ O (30 mL) was added to pyridine (35 mL).Tris(8-hydroxymethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(0.400 g, 0.51 mmol (Example 33) was added under stirring, which wasmaintained at room temperature for two days. Pyridine and excessanhydride were evaporated (oil-pump) at 40°-50° C. to a syrup, which wastaken up in 70 mL of CH₂ Cl₂. The organic phase was washed with water(30 mL), 0.5M HCl (40 mL), water (50 mL) and NaHCO₃ (saturated, 30 mL).The organic phase was separated, dried and the solvent was evaporated,leaving a syrup, which crystallized after standing for ca 1 h and theproducttris(8-methylcarbonyloxymethyl-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanolwas isolated (0.460 g, 100%).

¹ H NMR (300 MHz, CDCl₃) δ: 1.48 (s. CH₃, 36H), 2.05 (s, CH₃ CO, 9H),5.25 (s, CH₂, 6H), 4.19 (s, OH, 1H)

Ms (Thermospray): M⁺ +23 (Na) 931.

EXAMPLE 23Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methaneandbis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)-(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane##STR45##

Tris(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)-dioxole-4-yl)methane(2.0 g, 3.5 mmol (Example 17)) was dissolved in dry ether (100 mL) atroom temperature. Under an inert atmosphere n-butyl lithium (6 mL) wasadded, and the reaction mixture was heated to reflux (15 min). At thistemperature another portion of n-butyl lithium (2 mL) was added and theheating was interrupted. After 5 min DMF (2.7 mL, 35 mmol) was carefullyadded and the reaction mixture was left stirring at room temperatureovernight. Water (100 mL) and glacial acetic acid (1.5 mL) were added tothe reaction mixture and the phases were separated. The aqueous phasewas extracted with water (2×50 mL), and dried over a mixture of Na₂ SO₄and K₂ CO₃. After filtering through a bed of SiO₂ the solvent wasevaporated leaving a yellow to red crystalline residue, which waschromatographed on a column of SiO₂ with CH₂ Cl₂ /ether (4:1) as eluent,yielding pure dialdehydebis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxol-4-yl)-(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxol-4-yl)methane0.610 g (20%) and trialdehydetris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxol-4-yl)methane1.23 g (51%).Bis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)-(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxol-4-yl)methane:

¹ H NMR (300 MHz CDCl₃) δ: 1.50 (s, CH₃, 12H) 1.55 (s, CH₃ 24H) 5.42 (s,C--H, 1H) 6.24 (s, aromatic H, 1H) 10.06 (s, CHO, 2H).

¹³ C NMR (75 MHz, CDCl₃) d:185.59, 140.19, 140.15, 139.67, 139.59,119.46, 117.15, 113.10, 105.36, 105.21, 91.40, 31.43, 25.52, 25.36.

MS (Thermospray): M⁺ +23 (Na) 770.

Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxole-4-yl)methane:

¹ H NMR (300 MHz, CDCl₃) δ: 1.56 (s. CH₃, 36H) 5.44 (s. C--H, 1H) 10.07(s. CHO, 3H).

¹³ C NMR (75 MHz, CDCl₃) δ: 185.5 (C═O) 140.3 140.1 (arom C--O) 119.7(alif. O--C--O) 111.9 (quart. arom C) 105.4 (p-sub. quart. arom C) 31.7(C--H) 25.6 (CH₃).

IR (KBr, cm-1): 1700 (s. C═O) 2980 (m, C--H str) 1040 (s. Ar--O--C).

MS (Thermospray): M⁺ +23 (Na) 783.0.

EXAMPLE 24Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxole-4-yl)methyl##STR46##

Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxole-4-yl)methane(140 mg, 0.18 mmol, Example 23) was dissolved in a mixture of dry DMSO(15 mL) and of dry ether (50 mL). NaH (5 mg, 0.19 mmol) and t-BuOK(catalytic amount) were added under N₂ -atmosphere. The color of thesolution changed from yellow to deep green-blue. After 4 h of stirringat room temperature under N₂ I₂ (46 mg, 0.18 mmol) was added, and after2 min the reaction mixture was poured into a saturated solution of Na₂S₂ O₃ (100 mL). The organic phase was separated, dried (Na₂ SO₄) and thesolvent was evaporated leaving a black crystalline residue weighing0.120 g (88%).

MS (Thermospray): M⁺ +23 (Na) 782.0.

Radical content (NMR method) >50%.

ESR: 4 lines (internal ratio 1:3:3:1) with line widths of ca 70 mG.

Overhauser enhancements: 9 mW: 13 18 mW: 25 5 mW: 152 5 mW: 254 afterdilution to 10 mM.

EXAMPLE 25Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxol-4-yl)methyl##STR47##

Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(200 mg, 0.20 mmol) was dissolved in of dry THF (15 mL) and SOCl₂ (80mg, 0.20 mmol) was added. After stirring at room temperature for 2 h thesolvent was evaporated (<70° C.) and the residue was pumped dryovernight. The orange producttris(8-formyl-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']-bis(1,3)-dioxol-4-yl)methylchloridewas dissolved in of dry THF (15 mL) and BCl₃ (0.26 mL, 1M in CH₂ Cl₂)was added at room temperature and the solution immediately turned black.After 0.5 h of stirring under N₂ -atmosphere was added; first SnCl₂(0.15 g, 0.80 mmol) and then Zn(Hg), (0.15 g, 2.20 mmol) (prepared bytreating 120 g zinc powder with a mixture of 12 g HgCl₂, 6 mL conc. HCland 150 mL of water for 5 min. and decanting off the liquid). Stirringwas maintained for 0.5 h. The reaction mixture was applied to a column(1 cm diameter) consisting of 3 cm of SiO₂ at the bottom and 15 cm ofChelex 100 on top. Elution was performed with dry THF under N₂-atmosphere. The eluent was evaporated to dryness, leaving a brown-blackcrystalline residue (0.19 g, 100%).

Radical content was ca 27% according to HPLC (ion pair,tetrabutylammoniumacetate, SiO₂ C18, CH₃ CN/H₂ O (75:25)).

ESR spectrum of 4 peaks (int ratio 1:3:3:1) with 70 mG linewidth.

EXAMPLE 26Tris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methyl##STR48##

Tris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxol-4-yl)methanol(240 mg, Example 15) was dissolved in of dry THF (25 mL) and SOCl₂ (38mg, 23 L) was added at room temperature. Stirring was maintained for 2.5h. The solvent of the reaction mixture was then evaporated to dryness(<70° C.). After pump drying over nighttris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methylchloridewas dissolved in of dry THF (25 mL) and, in turn SnCl₂ (0.10 g, 0.53mmol) and then Zn(Hg) (see Example 25) (0.10 g, 1.52 mmol) were addedunder N₂. The solution turned black and was filtered through a column (1cm diameter) of 15 cm Chelex 100 (top) and 3 cm of SiO₂ (bottom), underN₂ with THF as eluent. The solvent was evaporated leaving a blackcrystalline residue (0.20 g).

ESR spectrum showed 10 lines with linewidths=48 mG. A radical content ofca 5% was estimated by ESR. At 75 mW, the Overhauser enhancement was 80.

EXAMPLE 27Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol##STR49##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (2.22 g, 10 mmol(Example 5)) was dissolved in dry tetrahydrofuran (dried using sodiumbenzophenone ketyl) and cooled to -78° C. under argon. n-Butyllithium(4.25 mL, 2.5M in hexane, 10.6 mmol) was added. The cooling bath wasremoved 35 minutes later and the mixture stirred for 40 minutes, whendry sulfur (S8, 0.320 g, 1.25 mmol) was added in one portion. The sulfurhad dissolved one hour and fifteen minutes later. The reaction mixturewas then recooled to -78° C. and n-butyllithium (4.25 mL, 10.6 mmol) wasadded. The dry ice/acetone bath was exchanged with a water/ice bath. Thenew cooling bath was removed after one hour and forty five minutes. Cold(-78° C.) diethylcarbonate (0.363 mL, 3 mmol) in THF (10 mL) wascannulated into the reaction mixture over a period of 10 minutes. Theresulting mixture was kept at (-70)°-(-78)° C. for two hours, followedby a period of one hour and thirty minutes at approximately 0° C.(ice/water bath). The mixture was then stirred till noon the followingday without addition of ice, at which time the temperature inside thereaction flask was +16° C. The mixture was then stirred without externalcooling for three more hours, poured into a half saturated sodiumdihydrogenphosphate buffer (100 mL) and extracted with diethylether(4×100 mL). The organic phase was washed with the same buffer (50 mL)and dried (MgSO₄). This yielded 2.93 g of product, which by 1H NMR (300MHz, CDCl₃) was shown to contain approximately 50% oftris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxol-4-yl)methanol.The was used immediately in the next step.Tris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-b is(1,3)dioxol-4-yl)methanol (2.93 g, 50%, 1.86 mmol) was dissolved in dryDMF (100 mL) under argon. K₂ CO₃ (4 g) was added and the solution cooledto the freezing point. Ethylchloroacetate (5 mL, 46.7 mmol, Janssen11822.85) was added, and the reaction mixture was stirred at roomtemperature overnight. Most of the DMF and excess ethylchloroacetatewere removed by high vacuum distillation at 30°-40° C. The residue wasmixed with saturated sodium dihydrogenphosphate buffer (100 mL) andextracted with diethyl ether (4×150 mL). The etheral phase was washedwith phosphate buffer (2×50 mL) and water (50 mL), dried (MgSO₄) andevaporated. Purification was achieved through two flash chromatography(E. Merck 0.040-0.063 mm SiO₂) separations with n-heptane:ethyl acetate(1:1), followed by straight phase (E. Merck 20-45 mm CH₂ Cl₂ :EtOAc 9:1)and reversed phase (Prep-pak C18, MeOH:H₂ O, 8:2, 15% CH₂ Cl₂ inapplication volume) HPLC chromatography, and finally recrystallizationfrom diisopropyl ether. Yield (1.57 g 15% 15 mmol).

UV (maxima/minima): 220 (p), 249(v), 259(p), 297(v), 344(p). Otherspectroscopic data; see Example 9.

EXAMPLE 28Tris(8-ethoxycarbonylmethylthio-2,2,6,6,-tetramethylbenzo([1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methyl##STR50##

Tris(8-ethoxycarbonylmethylthio-2,2,6,6,-tetramethylbenzo([1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(2.00 g 1.91 mmol) (prepared as described in Example 27) was dissolvedin dry (sodium benzophenone ketyl) degassed (Ar) THF (1.0 L) in aseparatory funnel (2.0 L). A rapid stream of argon was bubbled throughthe solution. Borontrifluoroethyl etherate (2.88 mL 48% Fluka 15720) wasadded with a syringe. The clear solution turned immediately dark blue,indicating formation of the corresponding cation. Tin(II)chloride (2.90g 15.3 mmol E. Merck 818150) was added. The color changed from blue tocolorless to geen in a couple of minutes, and the resulting mixture wasbubbled with argon for 10 minutes, when Zinc (2.50 g, 38.2 mmol Janssen19.834.46) (activated by treatment with 1M hydrochloric acid followed bywater, ethanol and diethylether washings and high vacum drying) wasadded. The argon bubbling was continued for another 20 minutes, whenmore zinc (2.5 g) was added. 45 Minutes later the last amount of zinc(3.0 g) was added, followed by borontrifluoroethyl etherate (1.44 mL).The reaction was continously monitored by HPLC. The substrate and theradical separated on an analytical RP18 column (Nucleosil 5 mm) withacetonitrile:water (75:25) containing the ion pair tetrabutylammoniumacetate (5 mM) (pH 6.7). The detector system consisted of a diode arrayUV detector (Varian 9065 polychrome). The radical was distinguished fromthe substrate by the UV spectra (see below). The reaction was stoppedwhen the radical content reached a maximum (˜90% by UV, not consideringdifferent extinction coefficients). The volume of the reaction mixturewas reduced to about 700 mL during the reaction period. The reactionmixture was diluted with dry (sodium benzophenone ketyl) diethylether(1.0 L) and extracted with dry, oxygen free sodium hydroxide (2×100 mL,2M, 0° C., He). The organic phase was filtered through a SiO₂ column (40cm long, I.D. 5 cm, E. Merck 9385 0.0040-0.063 mm). The column waspreconditioned with dry oxygen free diethylether before the filtration.The last portion of the radical was eluted with pure diethylether(sodium benzophenone ketyl, Ar). The radical was obtained as black/greencrystals after evaporation under argon. Yield (1.87 g, 1.814 mmol, 95%).

MS (Thermospray): M⁺ +23 (Na) 1052.

UV (Absorbtion maxima/minima): 195(p), 229(sh), 302 (v), 339(p), 348(v).

ESR (THF): 7 lines, lw 30 mG, aH 60 mG.

Overhauser (THF less than 1 mM conc., 200 G): freq. 548.9 MHz, 9 mW 78enhancement, 18 mW 116 enhancement.

EXAMPLE 29 Tris(2,2,6 6-tetramethylsodium-8-carboxylatomethylthiobenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methyl##STR51##

Tris(8-ethoxycarbonylmethylthio-2,2,6,6,-tetramethylbenzo-[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methyl(1.97 g, 1.91 mmol 90% pure) was dissolved in a degassed (heliumfollowed by argon) mixture of dioxane (Lab Scan C2512 HPLC quality) andwater (200 mL (3:1)). Sodium hydroxide (4.3 mL, 2M, 8.58 mmol, He, Ar,0° C.) was added and the hydrolysis performed in a ultrasound bath(Sonorex RK 2555). The reaction was followed by HPLC, RP18 column(Nucleosil 5 mm) with acetonitrile:water (75:25) containingtetrabutylammonium acetate (5 mM, pH 6.7). The detector system consistedof a diode array UV detector--Varian 9065 polychrome). During thereaction the diester- and monoester radicals were observed as well asthe tricarboxylic acid salts. The reaction mixture was frozen when theHPLC analysis showed pure tricarboxylic acid sodium salt (mixture ofradical and carbinol) and subjected to freeze drying. Yield (2.07 g,100% 1.90 mmol) of a black/brown, fluffy material, containing excessNaOH. Radical content: 50% (NMR--Evans method).

ESR (H₂ O 0.3 mM, 200 G): 7 lines, Lw 27 mG, a_(H) 60 mG, 200 G, Freq.548.9 MHz.

Overhauser: (H₂ O 0.3 mM, 200 G): Freq. 548.9 MHz, 9 mW 63 enhancement,18 mW 81 enhancement.

EXAMPLE 308-Mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole##STR52##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (30.0 g, 135 mmol(Example 5)) was dissolved in dry (sodium benzophenoneketyl)diethylether (250 mL), and heated to reflux. n-Butyllithium (50 mL,2.68M in toluene, 134 mmol) was added and the reflux continued one hour.The flask was cooled to -78° C. and sulfur (4.297 g, 134 mmol) added.The cooling bath was exchanged with an ice/water cooling bath and thereaction mixture was stirred for one hour before alkaline water wasadded (150 mL, 1M, degassed with argon) followed by vigorous stirring inten minutes. The phases were separated and the water phase was washedwith diethylether (100 mL, degassed with argon). The water phase wasacidified with HCl (5M). The precipitated crystals were taken up indiethylether (degassed argon), dried (MgSO₄) and evaporated to dryness.The pure crystals are stable for weeks under argon in the freezer.Yield: 24.86 g (72.5%).

¹ H NMR (CDCl₃, 300 MHz) δ: 1.65, 3.28, 6.13.

¹³ C NMR (CDCl₃, 75 MHz) δ: 139.87, 138.33, 118.31, 94.99, 90.23, 25.54.

EXAMPLE 31Tris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR53##

8-Mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole (24.9g, 97.9 mmol (Example 30)) was dissolved in dry diethylether (200 mL) ina three necked round-bottomed flask, equipped with a sintered glassfilter (no. 4) at one of the outlets. The reaction mixture was cooled to(-78)° C. and n-butyllithium (36.5 mL, 97.9 mmol, in toluene) was added.The dry ice/acetone bath was exchanged with a water/ice bath. The newcooling bath was removed after one hour. The solvent, and most of thesoluble impurities were removed from the lithium salt by filtrationthrough the sintered glass filter. The whole filtration took about tenminutes. The salt was washed to the bottom of the flask with drydiethylether (30 mL). Tetrahydrofuran (250 mL, sodium benzophenone ketyldried) was added and the solution was cooled to (-78° C.). n-Butyllithium (36.5 mL, 97.9 mmol, in toluene) was added. After a period often minutes, the temperature was gradually raised to 0° C. with awater/ice bath. The mixture was stirred with this cooling for one hourand twenty minutes, followed by a period of thirty minutes at roomtemperature. After recooling to (-78)° C., diethylcarbonate (3.63 mL, 30mmol) in tetrahydrofuran (20 mL) was added to the reaction mixture overa period of one minute. The temperature was raised gradually with thehelp of a water/ice bath. The reaction was followed by taking samples(quench of small samples in sodium dihydrogenphosphate buffer underargon, evaporating organic phase) and running ¹ H NMR. The trimerisationwas complete after four hours. The mixture was quenched with sodiumdihydrogenphosphate buffer (saturated, 130 mL), stirred twenty minutesand the phases were separated. The water phase was extracted withdiethylether (50 mL, argon) and the organic phases were combined, washed(sodium dihydrogen phosphate buffer, 30 mL), dried (MgSO₄, 30 min) andevaporated to dryness. Diethylether (dry, argon) was added to the brownoil to induce the crystallization. Upon the dissolution of the oil thetitle compound crystallized as porous yellow crystals. The product wasisolated by filtration.

Yield: 10.0 g (12.7 mmol, 39%).

¹ H NMR (CDCl₃, 300 MHz) δ: 1.49, 3.25, 4.10.

¹³ C NMR (CDCl₃, 75 MHz) δ: 138.54, 138.26, 117.51, 110.16, 93.55,72.33, 25.53.

MS (Thermospray): M⁺ +23 (Na) 811.

Crystallization of the mother liquor gave (¹ H NMR) 0.8 g of dimeric(ketone) product. (See Example 51).

EXAMPLE 32Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol##STR54##

The title compound was made with puretris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(from Example 31) (2.10 g 2.67 mmol) and ethylchloroacetate (16.0 mmol),using a procedure analogous to that described in Example 27. Yield 1.93g (98%).

¹ H NMR (CDCl₃, 300 MHz) δ: 4.12, 3.54, 1.51, 1.24.

¹³ C NMR (CDCl₃, 75 MHz) δ: 169.00, 141.22, 138.64, 117.75, 112.40,96.62, 72.48, 61.20, 35.47, 25.42, 14.08.

EXAMPLE 33Tris(8-hydroxymethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)-dioxol-4-yl)methanol##STR55##

Tris(2,2,6,6-tetramethylbenzo([1,2-d:4,5-d']-bis(1,3)dioxol-4-yl)methanol(6.35 g, 9.38 mmol) was dissolved in dry diethylether (200 mL) underargon and cooled to 0° C. n-Butyllithium (22.5 mL, 56.30.10-3 mol) wasadded and the temperature was increased to induce reflux. The reactionmixture was refluxed for 25 minutes. After cooling to 0° C., dryformaldehyde (gas, formed by sublimation) (4.0 g, 133 mmol) was addedand the resulting mixture was stirred over night while the temperaturegradually was increased to room temperature. After quenching with sodiumdihydrogenphosphate buffer (200 mL, saturated), extraction withdiethylether (5×250 mL), drying (MgSO₄) and evaporation, the product wasisolated by column chromatography (E. Merck 0.040×0.063 mm SiO₂, 6.27cm, CH₂ Cl₂ :EtOAc 3:2 (2.0 L), CH₂ Cl₂ :EtOAc (1:1) (2.0 L), CH₂ Cl₂:EtOAc (2:3) (2.0 L). Yield 0.239 g (0.305 mmol (3.3%).

¹ H NMR (300 MHz, CDCl₃) δ: 4.59 (s, CH₂, 6H), 1.23 (s, CH₃, 36H), OHnot seen.

¹³ C NMR (75 MHz, CDCl₃) δ: 138.70, 139.38, 117.23, 105.88, 72.51,56.66, 25.48.

EXAMPLE 34Tris(8-methoxymethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d'](1,3)dioxole-4-yl)methanol##STR56##

Tris(8-hydroxymethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d'](1,3)dioxole-4-yl)methanol(0.105 g, 0.134 mmol (Example 33)) and a catalytic amount oftetrabutylammoniumhydrogen sulfate were added to a preformed solution ofdimethylsulfate (0.2 mL) and sodium hydroxide (50%, 1.0 mL) in CH₂ Cl₂(2 mL). The resulting solution was stirred at ambient temperature for 48hours. The mixture was evaporated and the resulting oil chromatographedon silica (CH₂ Cl₂ :diethylether (5:1)). The major product was notcompletely pure according to TLC, but upon dissolution in CDCl₃ theimpurities did not dissolve. Evaporation of the filtered solutionyielded 94 mg (0.114 mmol, 85%) of pure title compound.

¹ H NMR (300 MHz, CDCl₃) δ: 4.40 (s, CH₂, 6H), 3.30 (s, CH₃, 9H), 1.47(s, CH₃, 36H), OH not seen.

¹³ C NMR (75 MHz, CDCl₃) δ: 139.64, 138.58, 116.97, 112.37, 102.65,72.61, 63.49, 57.16, 25.46.

EXAMPLE 35Tris(8-methoxymethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl##STR57##

Tris(8-methoxymethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(94.0 mg, 0.114 mmol (Example 34)) and thionyl chloride (40 mL, 0.57mmol) were stirred in tetrahydrofuran (2 mL) (sodium benzophenone ketyldried) for 45 minutes and evaporated. The residue was dissolved in freshtetrahydrofuran (10 mL) and boron trichloride (330 mL, 1M in CH₂ Cl₂).The color of the solution turned light brown. Tin(II)chloride (127 mg,0.986 mmol) was added 10 minutes after the boron compound, and zinc (187mg, 2.85 mmol) was added after another 15 minutes. One hour and fifteenminutes later the reaction mixture was green. The solution wasevaporated, and subsequently filtered through a SiO₂ column withtetrahydrofuran as the eluent. The residue (80 mg, 0.099 mmol, 87%(containing some radical precur) was dissolved in tetrahydrofuran andthe radical characterized by ESR and Overhauser enhancements:

ESR (200 G): Linewidth 1.5 G (70 overlapping lines). Overhauserenhancements (548.9 MHz, 200 G): 5 W 60 enhancements.

EXAMPLE 36Tris(8-hydroxyethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol##STR58##

LiAlH₄ (15.2 mg, 0.40 mmol) was added to a solution oftris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(10.5 mg 0.10 mmol (Example 27)) in diethyl ether (10 mL) under nitrogenat 20° C. The reaction was followed by HPLC (reversed phase C18,acetonitrile:water (3:1), 5 mM tetrabutylammonium acetate). The mixturewas quenched with ethylacetate when no more substrate was seen by HPLC.Dilute sulfuric acid was then added until pH 6-7. The ether phase wasseparated, and the water phase was extracted with diethyl ether. Thecombined etheric phases were dried (MgSO₄) and evaporated, yielding0.0901 g (97.8%, 0.0978 mmol) of a yellowish oil, which graduallycrystallized upon standing.

¹ H NMR (300 MHz, Acetone d₆) δ: 1.49 (s, CH₃, 36H), 2.51 (bs, OH, 3H),2.59 (t, CH₂, 6H), 4.38 (s, OH 1H).

¹³ C NMR (75 MHz, Acetone d₆) δ: 141.96, 138.93, 117.80, 112.52, 98.06,72.50, 60.98, 36.25, 25.18.

MS (Thermospray): M⁺ +23 (Na) 943, M⁺ -18 902.

EXAMPLE 37Tris(8-hydroxyethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methyl##STR59##

LiAlH₄ (95.8 mg, 2.52 mmol) was added to a solution oftris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-δ:4,5-d']-bis(1,3)dioxole-4-yl)methyl(1.30 g, 1.26 mmol, 50% radical content (Example 28)) in diethylether(50 mL) under nitrogen at 20° C. The reaction was followed by HPLC(reversed phase C18, acetonitrile:water (3:1), 5 mM tetrabutylammoniumacetate). The mixture was quenched with ethylacetate when no moresubstrate was seen according to HPLC. Dilute sulfuric acid was thenadded until pH 6-7. The ether phase was separated, and the water phaseextracted with diethylether (2×100 mL). The combined etheric phases weredried (Na₂ SO₄) and evaporated, yielding 0.96 g (84%, 1.06 mmol) of ayellowish oil. The product was characterized by ESR and Overhausermeasurements. HPLC chromatography in combination with diode arraydetection and UV spectral analysis showed a radical content of about6-7% after evaporation overnight.

EXAMPLE 38Tris(8-di(methylcarbonyloxyethyl)aminocarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol##STR60##

Tris(8-ethoxycarbonylmethylthio-2,2,6,6,-tetramethylbenzo-([1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(0.4675 g, 0.446 mmol (Example 27)) and diethanolamine (0.939 g, 8.93mmol) were mixed and aminolysis was performed in toluene at refluxtemperature under nitrogen for thirty six hours. At this time HPLCanalysis (reversed phase C18, acetonitrile:water (3:1), 5 mMtetrabutylammonium acetate, 254 nm UV detection) showed completeconsumption of the starting material. The crude reaction mixture wasevaporated and checked with ¹³ C NMR without removing the excessdiethanol amine from the intermediarytris(8-di(hydroxyethyl)aminocarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol:[(CD₃ OD, 75 MHz) δ: 171.34, 142.55, 139.97, 119.12, 112.99, 98.94,60.73, 60.58, 52.97, 50.36, 36.84, 25.88, central COH at ca. 72 ppm wasnot seen.] and redissolved in a mixture of pyridine (7.0 mL) and aceticanhydride (5.0 mL) and stirred over night at room temperature. TLCanalysis (SiO₂, methanol:ethylacetate (3:7)) showed formation of a morelipophilic product. This product was purified by two consecutivechromatographic separations on SiO₂ (E. Merck 0.040-0.063 mm). The firstcolumn was eluted with n-heptane:ethylacetate (1:1) andethylacetate:ethanol (1:1). The second column was eluted withethylacetate/n-butanol (95:5). The solvents were evaporated and the lastamounts of butanol was removed by high vacuum evaporation under a periodof forty eight hours. Yield 0.151 g (23%, 0.102 mmol) (about 20% moresubstance in the impure fractions).

¹ H NMR (CDCl₃, 300 MHz) δ: 4.23 (t, CH₂, 6H), 4.15 (t, CH₂, 6H), 3.74(s, CH₂, 6H), 3.70 (t, CH₂, 6H), 3.54(t, CH₂, 6H), 2.02 (s, CH₃, 18H),1.49 (s, CH₃, 36H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 170.63, 170.37, 168.40, 141.30, 138.60,117.72, 112.38, 96.38, 72.45, 61.85, 61.83, 47.78, 45.52, 35.43,25.39,20.78, 20.66, (61.85 and 61.83 are nonequivalent possibly due toresticted rotation arising from the amide).

MS (Thermospray): M⁺ +23 (Na) 1495, 1496, 1497 and 1498 (scale notcalibrated).

EXAMPLE 39Tris(8-carboxylmethylthio-2,2,6,6-tetramethylbenzo-[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol##STR61##

Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(4.00 g, 3.819 mmol (Example 27)) was dissolved/suspended in a mixtureof water and ethanol (200 mL, (1:1)) and cooled to approximately 5° C.Sodium hydroxide (15.3 mL, 1.0M, 15.3 mmol) was added and the reactionwas followed by HPLC. The next day more sodium hydroxide (3.82 mL, 1.0M,3.82 mmol) and (7.64 mL, 1.0M, 7.64 mmol) was added. The ethanol wasevaporated after complete conversion had been observed (HPLC). Thealkaline aqueous phase was extracted with heptane (2×100 mL) and thenacidified with HCl (2.0M) to pH 5. The product was taken up indiethylether (2×100 mL). Upon further acidification of the aqueous phase(to pH 3), more precipitate was formed. This was also taken up indiethylether (2×100 mL). The combined ether phases were extracted oncewith water (100 mL) and dried (Na₂ SO₄). Evaporation yielded 3.11 g(3.23 mmol, 85%) of a white crystalline material. When the material wasdried at very high vacuum and high temperature the substance turnedblue, possibly due to the formation of an internal zwitter ion. Uponexposure to moist air the white color returns.

¹ H NMR (300 MHz, DMSOd₆) δ: 12.55 (bs, COOH, 3H), 3.59 (s, CH₂, 6H),3.31 (bs, OH, 3H), 1.44 (s, CH₃, 36H).

¹³ C NMR (75 MHz, DMSOd₆) δ: 170.04, 140.18, 138.17, 117.17, 111.83,97.13, 71.47, 34.70, 24.98.

MS (Electrospray): Calc. 962.17, found 962.17. Titration with sodiumhydroxide (0.01M) gave a purity (% of molecules with three carboxylicacids) of 99.7%±1.9% (SD).

EXAMPLE 40 8-Hydroxy-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-(1,3)dioxole##STR62##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']-(1,3)dioxole (5.00 g, 22.5 mmol(Example 5)) was dissolved in diethyl ether (150 mL, sodium benzophenoneketyl) under argon. n-Butyl lithium (10.0 mL, 25 mmol, 2.5M in toluene)was added at room temperature followed by methyl magnesium bromide (4.25mL, 13 mmol, 3.0M in diethyl ether, Aldrich). the resulting mixture wasstirred at room temperature for 1 h. Oxygen was bubbled through thesolution over a period of 2 hours, while cooling with a cold water bath.The reaction mixture was poured into a solution of NaOH (50 mL, 1M) andextracted with diethyl ether (100 mL). The aqueous phase was acidifiedwith conc. HCl to pH 2 while stirring. The product was isolated byextracting with diethyl ether (3×50 mL). The ether was dried (Na₂ SO₄)and evaporated yielding 1.50 g (6.3 mmol, 28%) of8-hydroxy-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole.

¹ H NMR (300 MHz, DMSOd₆) δ: 6.00 (s, aromatic H, 1H), 1.66 (s, CH₃,12H).

MS(Thermospray): M⁺ +23 (Na₊) 261

EXAMPLE 41 8-Methoxy-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-(1,3)dioxole##STR63##

8-Hydroxy-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-(1,3)dioxole (1.00 g,4.20 mmol (Example 40)) was dissolved in CH₂ Cl₂ (30 mL) and dimethylsulfate (0.6 mL, 6.30 mmol), tetrabutyl-ammonium hydrogensulfate(catalytic amount) and sodium hydroxide (1.0 mL, 40%) were added. Theresulting mixture was stirred at room temperature for 24 hours. Thephases were separated and the aqueous phase was extracted with diethylether (2×50 mL). The combined organic solution was extracted withammonia (25 mL, 25%) and water (50 mL), dried (Na₂ SO₄) and evaporated.Yield 0.9 g (83%) of a yellow oil.

¹ H NMR (CDCl₃, 300 MHz) δ: 6.05 (s, CH, 1H), 4.02 (s, CH₃, 3H), 1.65(s, CH₃, 12H).

MS(Thermospray): M⁺ +23 (Na+) 275.

EXAMPLE 42Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane##STR64##

Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(1.06 g, 1.01 mmol (Example 27)) was added to a solution of trimethylsilylchloride (0.767 mL, 6.07 mmol) and sodium iodide (0.91 g, 6.07mmol) in acetonitrile (50 mL) and stirred for ten minutes. Saturatedsodium thiosulfate (30 mL) was added, followed by diethylether (70 mL),and the mixture was stirred for 10 minutes. The phases were separatedand the organic phase was washed with water (30 mL). The organic phasewas diluted with more ether (100 mL), since crystals had started to formin the funnel. The solution was kept in the freezer over night afterdrying (MgSO₄) and filtration. The crystals formed were removed(impurity) and the solution evaporated to dryness. The product waspurified by dissolving the substance at room temperature in diispropylether (E. Merck 118867, 30 mL), followed by bubbling with helium. Theflask was stoppered and put in the refrigerator for two and a halfhours. The product was collected by filtration (glass sinter no. 3), andthe mother liquor was evaporated to approximately half the volume. Thetotal yield after collecting the second crop was 640 mg (0.621 mmol,61%).

¹ H NMR (300 MHz, CDCl₃) δ: 1.23 (t), 1.51 (s), 3.55 (s), 4.11 (q), 5.34(s).

¹³ C NMR (75 MHz, CDCl₃) δ: 169.09, 140.810, 139.50, 117.81, 107.65,95.37, 61.18, 35.71, 30.70, 25.38, 14.11.

MS (Thermospray): M⁺ +23 (Na) 1053.

EXAMPLE 43Tris(8-dimethylaminocarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR65##

Tris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methanol(1.00 g, 1.27 mmol (Example 31)) was added to an oxygen free (argonbubbling five min.) solution of K₂ CO₃ (5.00 g) and dimethylcarbamoylchloride (Fluka 39871, 0.367 mL, 4.0 mmol). A sample taken after fortyfive minutes, and controlled by ¹ H NMR, showed complete consumption ofthe substrate. The solution was filtered and evaporated. The crudeproduct was 93% pure according to HPLC (C8, CH₃ CN:H₂ O, (3:1), 254 nm).

The substance was dissolved in diethylether (30 mL, dry, sodiumbenzophenone ketyl) and ultrasonicated for five minutes, followed byrotation at 35° C. for five minutes on a rotavapor at normal pressure.Cooling in the freezer for thirty minutes gave greyish crystals. Yield0.580 g (0.579 mmol, 45.6%).

¹ H NMR (300 MHz, CDCl₃) δ: 1.54 (s), 3.3 (bd), 4.20 (bs).

¹³ C NMR (75 MHz, CDCl₃) δ: 163.02, 142.80, 138.78, 118.05, 113.52,92.07, 72.63, 37.01, 25.45.

MS (Thermospray): M⁺ +23 (Na) 1024.

EXAMPLE 44Tris(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR66##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (17.570 g, 79.0mmol (Example 5)) was dissolved in THF (300 mL, sodium benzophenoneketyl) and cooled to -20° C. with an ethanol/dry ice bath whilemaintaining an argon atmosphere. n-Butyl lithium (37.8 mL, 2.5M inhexane, 95.0 mmol) was added with a syringe, and the resulting mixturewas allowed to reach room temperature. The mixture was recooled to -20°C. and dimethyl carbonate (2.37 g, 2.20 mL, 26.0 mmol) was added. Thecooling bath was removed and the reaction mixture was stirred at roomtemperature for 3.5 hours. The mixture was then poured onto ice/watercontaining HOAc (2%) and extracted with diethyl ether (2×300 ml). Theorganic phase was washed with water (2×100 mL) and dried (Na₂ SO₄). Thesolvent was evaporated and the product triturated with petroleum ether.Yield 13.56 g (74.4%)

¹ H NMR (CDCl₃, 300 MHz) δ: 6.26 (s, arom. H, 3H), 1.48 (s, CH₃, 36H),4.28 (s, OH, ¹ H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 140.10, 139.00, 116.71, 112.57, 91.64,72.69, 25.38.

MS (Thermospray): M⁺ +23 (Na) 715.

EXAMPLE 45Tris(8-ethyloxycarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR67##

Tris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(1.000 g, 1.269 mmol Example 31) was added to a solution of acetonitrile(75 mL, argon bubbled) and potassium carbonate (6.0 g). ClCO₂ Et (0.725mL, 8.00 mmol) was added and the resulting mixture was vigourouslystirred for 30 minutes. An NMR sample showed complete conversion at thistime. The mixture was filtered and evaporated. The pure product wasobtained by chromatography on a silica column eluting with ethylacetate:heptane 1:1. Yield 1.26 g (98.7%).

¹ H NMR (CDCl₃, 300 MHz) δ: 4.26 (q, CH2, 6H), 4.21 (s, COH, ¹ H), 1.54(s, CH₃, 36H), 1.30 (t, CH₃, 9H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 166.18, 142.30, 138.80, 118.35 113.70,91.26, 72.51, 64.09, 25.42, 14.22.

MS (Thermospray): M⁺ +23 (Na) 1027.

EXAMPLE 46Tris(8-ethyloxycarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl##STR68##

Tris(8-ethyloxycarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(0.100 g, 0.099 mmol, Example 45) was dissolved in THF (5 mL, sodiumbenzophenone ketyl) and SOCl₂ (0.073 mL, 0.998 mmol) was added. Themixture was stirred for 3 hours and then evaporated under argon. MoreTHF (3×50 mL, sodium benzophenone ketyl) was added and evaporated aftereach addition. The residue was dissolved in THF (50 mL, sodiumbenzophenone ketyl) and BCl₃ (955 mL, 0.998 mmol, 1M soln. in CH₂ Cl₂)and stirred for 15 minutes, when SnCl₂ (0.189 g, 0.999 mmol) was added.The mixture was stirred for 10 minutes and zinc (0.653 g, 9.985 mmol,specially activated by p.a. HCl (2M), water, ethanol, ether, high vacuumdrying 250° C. the same day)) was added. The reaction mixture was workedup after 3 hours stirring, by diluting with dry, oxygen-free diethylether (300 mL), extracting with NaOH (2×50 mL, 2M, oxygen free) andfiltering the solution through a silica column, eluting with ether.Yield 0.058 g, (0.0594 mmol 60%).

ESR (THF, 200 G): Linewidth 109 mG (one wide line containing 70resonances).

Overhauser enhancements (THF, 548.9 MHz, 200 G): 9 mW 12 enhancement, 18mW 25 enhancement.

EXAMPLE 47Tris(8-tertbutylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR69##

Tris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(1.000 g, 1.268 mmol, Example 31), pyridine (0.620 mL, 7.606 mmol) andN,N-dimethylamino-pyridine (catalytic amount) were added to degassed(argon bubbled) acetonitrile (50 mL) and cooled close to the freezingpoint. 2,2-Dimethylpropanoic acid chloride (0.940 mL, 7.606 mmol) wasadded with a syringe, and the reaction mixture was allowed to reach roomtemperature over a period of 4 hours. The solvent was evaporated and theresidue was dissolved in diethyl ether (200 mL). The ether was extractedwith NaH₂ PO₄ (50 mL, sat.), HCl (50 mL, 1M), NaH₂ PO₄ (50 mL, sat.) andNaCl (50 mL, sat.) and dried (Na₂ SO₃). Yield after filtration andevaporation: 1.00 g (0.9604 mmol, 75.7%). The compound was taken toanalytical purity by dissolving in diisopropyl ether (80 mL) at roomtemperature with the help of ultrasound. Cooling in the refrigerator for30 minutes gave 0.29 g (0.2785 mmol, 22.0%) of the pure compound.

¹ H NMR (CDCl₃, 300 MHz) δ: 4.21 (s, CH, ¹ H), 1.53 (s, CH₃, 36H), 1.30(s, CH₃, 36H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 200.00, 142.05, 138.87, 118.01,

MS (Thermospray): M⁺ +23 (Na) 1063.

EXAMPLE 48Tris(8-tertbutylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl##STR70##

Tris(8-tertbutylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(0.0957 g, 0.0919 mmol, Example 47) was dissolved in THF (25 mL, argonatmosphere, potassium benzophenone ketyl dried), and BF₃.OEt₂ (0.5 mL,48% in diethyl ether, Fluka) was added. After stirring for 5 minutesSnCl₂ (0.1249 g, 0.659 mmol) was added followed by a gradual change incolor to light brown. Zinc (0.5 g, 7.646 mmol) was added 1.5 hours afterthe SnCl₂. Two hours later the color had changed to green. A sampletaken (after letting the Zn settle) with a gas tight syringe showed alarge Overhauser enhancement. The reaction mixture was poured onto acolumn consisting of three layers; top layer SiO₂, intermediate layerSiO₂ and K₂ CO₃ 1:1 and bottom layer SiO₂. The K₂ CO₃ binds theBF₃.OEt₂, which has to be removed to avoid destabilizing thecorresponding cation radicals. Yield: 0.079 g (0.07713 mmol, 83.9%).

ESR (THF, 200 G): Linewidth 109 mG, one unresolved line. Overhauserenhancements (THF, 548.9 MHz, 200 G, conc.<1 mM): 9 mW 96 enhancement,18 mW 114 enhancement.

EXAMPLE 49Tris(8-methylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR71##

Tris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(1.000 g, 1.268 mmol, Example 31), acetyl chloride (0.540 mL, 7.605mmol) and K₂ CO₃ (2.0 g, 1.447 mmol) were added to CH₃ CN (25 mL,degassed with argon). An NMR sample showed complete reaction after 90minutes. The solvent was evaporated and the product was purified byflash chromatography (SiO₂, 230-400 mesh, i.d.35 mm, 40 cm length)followed by crystallization in diisopropyl ether (50 mL). The productwas dissolved at room temperature with the help of ultrasound. Theproduct was collected after 2 hours in the freezer. Yield: 0.61 g (0.667mmol, 52.6%)

¹ H NMR (CDCl₃, 300 MHz) δ: 2.42 (s, CH₃, 9H), 1.55 (s, CH₃, 36H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 190.58, 141.81, 138.86, 118.32, 113.55,91.44, 72.50, 29.97, 25.42.

MS (Thermospray): M⁺ +23 (Na) 937.

EXAMPLE 50Tris(8-methylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl##STR72##

Tris(8-methylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(0.0915 g, 0.0999 mmol, Example 49) was dissolved in THF (25 mL, argonatmosphere, potassium benzophenone ketyl dried), and BF₃.OEt₂ (0.5 mL,48% in diethyl ether Fluka) was added. A temporary red color was seenwhen the drops were hitting the surface of the solution. After stirringfor 5 minutes, SnCl₂ (0.1249 g, 0.659 mmol) was added followed by agradual change in color to light brown. Zinc (0.500 g, 7.646 mmol,prepared as described above) was added 1.5 hours after the SnCl₂. Twohours later the color had changed to green. A sample taken (afterletting the Zn settle) with a gas tight syringe showed an enormousOverhauser enhancement. The reaction mixture was poured onto a columnconsisting of three layers: top layer SiO₂, intermediate layer SiO₂ andK₂ CO₃ 1:1 and bottom layer SiO₂. The K₂ CO₃ binds the BF₃.OEt₂, whichhas to be removed to avoid destabilizing the corresponding cationradicals. Yield: 0.0720 g (0.0802 mmol, 80.3%, unknown radical content).

ESR (THF, 200 G): One line; Linewidth 117 mG. Overhauser enhancements(THF, 548.9 MHz, 200 G, <1 mM):11 mW 89 enhancement, 18 mW 110enhancement.

EXAMPLE 51Bis(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)ketone##STR73##

The title compound was isolated as a by product in the reaction betweendiethyl carbonate and the lithium salt of8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole, seeExample 31.

¹ H NMR (CDCl₃, 300 MHz) δ: 3.46 (s, SH, 2H), 1.63 (s, CH₃, 24H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 183.42, 138.96, 137.90, 119.55, 106.84,100.36, 15.24.

MS (Thermospray): M⁺ +23 (Na) 557.

EXAMPLE 52 Benzo[1,2-d:4,5-d']bis(1,3)dioxole-2,6-dispirocyclohexane##STR74##

1,2,4,5-Tetrahydroxybenzene (5.00 g, 35.00 mmol, Example 4) wasdissolved in THF (200 mL) and cyclohexanone (13.0 mL, 140.00 mmol) wasadded in one portion. P₂ O₅ was then added in small portions underefficient stirring. After addition was completed the temperature wasincreased to 80° C. for 4 hours. One large ball was formed in the flaskduring this time. After cooling to room temperature the ball was brokenup and the reaction mixture was poured on a mixture of ice (210 g) andNaOH (250 mL, 2M). Ether (100 mL) was added and the phases separated.The aqueous was extracted with ether (2×50 mL). The combined organicphase was dried (Na₂ SO₄), filtered and evaporated. The product wasdissolved in MeOH (20 mL), heated, filtered, cooled and the product wascollected by filtration. Yield 1.70 g (16%).

¹ H NMR (CDCl₃, 300 MHz) δ: 6.35 (s, CH arom., 2H), 1.87 (t, CH₂, 8H),1.69 (t, CH₂, 8H), 1.47 (m, CH₂, 4H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 140.37, 118.54, 92.80, 34.84, 24.57, 23.13.

EXAMPLE 53Tris(benzo[1,2-d:4,5-d']bis(1,3)dioxole-2,6-dispirocyclohexane)methanol##STR75##

Benzo[1,2-d:4,5-d']bis(1,3)dioxole-2,6-dispirocyclohexane (2.00 g, 6.60mmol, Example 52) was dissolved in diethyl ether (80 ml, dried over Al₂O₃) and cooled to -10° C. in an ice acetone bath. n-Butyl lithium (3.70mL, 2.5M in hexane) was added with a syringe over a period of fiveminutes. The mixture was stirred at the same temperature for 1 hour andovernight at room temperature. Diethyl carbonate (0.28 mL, 2.4 mmol) wasadded at room temperature and the mixture immediately changed color tored-brown. After stirring for 1 hour it was poured on ice/water (100mL). The organic phase was separated and the waterphase extracted withCH₂ Cl₂ (100 mL). To facilitate the phase separation HCl (20 mL, 1M) wasadded. The combined organic phase was dried (MgSO₄), filtered andevaporated. Yield 1.90 g (31%).

¹³ C NMR (CDCl₃, 75 MHz): 140.1, 138.9, 117.5, 91.5, 72.5, 34.6, 24.6,22.9.

EXAMPLE 54 1,2,4,5-Tetrahydroxybenzene ##STR76##

2,5-Dihydroxy-1,4-benzoquinone (4.00 g, 28.55 mmol) was suspended inwater (50 ml, distilled) followed by Na₂ S₂ O₄ (10.00 g, 57.47 mmol) andHCl (5.5 g, 55.75 mmol conc. soln.). The mixture was stirred 30 min. atroom temperature and evaporated to dryness. The residue was washed withTHF (40 ml) and filtered. The THF was evaporated yielding 2.00 g (14.07mmol, 49.3%) of the title substance.

¹ H NMR (DMSO6, 300 MHz) δ: 7.59 (bs, OH, 4H),6.23 (s, CH, 2H).

¹³ C NMR (DMSOd6, 75 MHz) δ: 136,96, 104.65.

EXAMPLE 55 1,2,4,5-Tetrahydroxybenzene ##STR77##

2,5-Dihydroxy-1,4-benzoquinone (10.00 g, 71.43 mmol) was suspended inwater (200 ml, distilled) followed by HCl (6 mL, 142.86 mmol, conc.).Iron (4.00 g, 71.43 mmol, powder) was added and the mixture was stirred30 minutes at room temperature. The solution was filtered and thesolution evaporated to dryness. The product was isolated as a grey brownpowder containing some iron complexes. Yield 14.80 g. The product isused as such in the reaction with acetone and P₂ O₅ (Example 5) with nonegative effects.

¹ H NMR (DMSOd₆, 300 MHz) δ: 6.9-3.0 (broad, OH, 4H), 6.21 (broad s, CH,2H).

¹³ C NMR (DMSOd₆, 75 MHz) δ: 136,96, 104.65.

EXAMPLE 56Tris(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR78##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (8.80 g, 40.00mmol, Example 5) was dissolved in THF (100 mL) and cooled to -20° C.n-Butyllithium (25.0 mL, 40.0 mmol, 1.6M) was added and the temperaturewas adjusted to ambient temperature over a period of 30 minutes and thenrecooled to -20° C.Bis(2,2,6,6-tetramethylbenzo-[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)ketone(18.80 g, 39.83 mmol, Example 57) was added and the temperature was oncemore adjusted to room temperature and the mixture was stirred for 18hours. The mixture was then poured on water/AcOH (100 mL, 2% AcOH) andextracted with diethyl ether (2×100 mL). The organic phase was washedwith water (2×100 ml) and dried (Na₂ SO₄). The solvent was evaporatedand the product was washed with petroleum ether (20 mL, 40°-60° C.).Yield 10.80 g (64.1%). Spectral data see example 44.

EXAMPLE 57Bis(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)ketone##STR79##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (400.0 g, 1.80mol, Example 5) was dissolved in THF (6 L, dried, perhaps incompletely)and cooled to -20° C. with a cryostat while maintaining a nitrogenatmosphere. n-Butyl lithium (1350 mL, 1.6M in hexane, 2.16 mol) wasadded with a dropping funnel, and the resulting mixture was allowed toreach room temperature. The mixture was recooled to -20° C. and dimethylcarbonate (47.0 mL, 0.56 mol) was added. The cryostat was turned off andthe reaction mixture was allowed to reach room temperature over nightwhile stirring. Water (3.0 L, containing 2% HOAc) was added to thereaction mixture, and the resulting solution was extracted with diethylether (2×3.0 l). The organic phase was washed with water (2×1.0 L) anddried (Na₂ SO₄, K₂ CO₃). The solvent was evaporated and the producttriturated with petroleum ether (boiling range 40°-60° C.). Yield afterseparation by recrystallisation in MeOH/H₂ O: 50.0 g (106.0 mmol, 18.9%relative to dimethyl carbonate).

¹ H NMR (CDCl₃, 300 MHz) δ: 6.42 (s, CH aromatic, 2H), 1.60 (s, CH₃,24H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 184.55 (C═O), 140.51, 139.43, 118.86,109.13, 95.89, 25.56.

MS (Thermospray): M⁺ +23 493.

EXAMPLE 58Mono-(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(phenyl)-mono(pyridin-4-yl)methanol##STR80##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (3.030 g, 13.60mmol, Example 5) was dissolved in THF (50 mL, sodium benzophenon ketyl)under N₂. The mixture was cooled to -78° C. n-Butyllithium (5.10 mL,13.6 mmol, 2.68M in toluene) was added with a syringe during 5 minutes.15 Minutes later the dry ice acetone cooling bath was excanged with aice water bath and the reaction mixture was stirred for 1 hour. Themixture was recooled to -78° C. and phenyl pyridyl ketone (2.50 g, 13.60mmol) dissolved in THF (10 mL, Na benzophenone ketyl) was addeddropwise. One hour later the cooling bath was exchanged with a ice/waterbath and the reaction was allowed to reach room temperature and stirredfor 3 days. The THF was washed with NaH₂ O₄ (2×50 mL, 1.25M), dried (Na₂SO₄) and evaporated yielding 5.10 g crude product. Analytically purecompound was obtained by dissolving the crude product in a mixture ofhot CH₃ CN and THF and crystallizing. Yield 0.826 g, (2.04 mmol 15%).

¹ H NMR (CDCl₃, 300 MHz) d 8.52 (m, CH pyridine, 2H, AA'in AA'XX'spinsystem), 7.26 (m, CH pyridin, 2H, XX'in AA'XX'spin system), 6.31 (s, CH,¹ H), 4.61 (s, OH, 1H), 1.47 (s, CH₃, 6H), 1.40 (s, CH₃, 6H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 153.90, 149.16, 143.79, 140.83, 137.41,127.85, 127.80, 127.53, 122.92, 118.17, 113.41, 110.08, 92.67, 79.28,25.21, 25.10 (two resonances at 25 ppm due to nonequivalence of methylgroups).

MS (Thermospray): M⁺ +1 406.

EXAMPLE 59Bis(8-methylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)ketone##STR81##

Bis-(8-Mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)ketone(0.6000 g, 1.1236 mmol Example 51) was dissolved in a CH₃ CN (50 mL) andcooled to 0° C. CH₃ I (0.42 ml, 6.74 mmol) and K₂ CO₃ (4.0 g) wereadded. The resulting mixture was stirred at room temperature for 70minutes. Before filtering away the K₂ CO₃, diethyl ether (50 ml) wasadded to ensure that all of the product was in solution. Filtration andevaporation yielded a quantiatative amount (0.630 g, 100 of the puretitle compound.

¹ H NMR (CDCl₃, 300 MHz) δ: 2.42 (s, CH₃, 6H), 1.55 (s, CH₃, 24H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 183.30, 140.15, 138.68, 118.94, 107.68,105.49, 26.57, 25.34, 16.12.

MS (Thermospray) M⁺ +23 (Na) 585, M⁺ +39 (Ka) 601.

EXAMPLE 60Bis(8-Methylmercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2-methylmercapto-pyrimidin-5-yl)methanol##STR82##

5-Bromo-2-methylthio-pyrimidine (0.250 g, 1.2195 mmol) was dissolved inTHF (50 mL, sodium benzophenone ketyl) and cooled to -105° C. n-Butyllithium (0.455 ml in toluene, 1.2195 ml) was added and the temperaturewas increased to -75° C. for 15 minutes and thereafter reduced to -105°C.Bis(8-methylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)ketone(0.63146 g, 1.1236 mmol, Example 59) was added in solid form and thetemperature was gradually increased to room temperature (removal ofcooling bath). The mixture was stirred overnight, NaCl (15 mL, sat.) anddiethyl ether (40 mL) were added and the phases separated after 5minutes stirring. The organic phase was dried (MgSO₄) and evaporatedyielding 0.59 crude product. Pure product was obtained bycrystallization in diethyl ether followed by a second crystallization indiisopropyl ether. Yield 0.115 g (0.1669 mmol, 14.9%).

¹ H NMR (CDCl₃, 300 MHz) δ: 8.53 (s, 2H), 4.54 (¹ H, s), 2.55 (s, 3H),2.41 (s, 6H), 1.49 (s, 24H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 171.12, 156.42, 141.21, 137.54, 131.33,118.26, 110.75, 101.18, 73.90, 25.38, 25.29.

MS (Thermospray) M⁺ +23 (Na) 711.

EXAMPLE 61Tris(8-methylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane##STR83##

NaI (0.15972 g, 1.1256 mmol) and trimethylsilyl chloride (0.142 mL,1.1256 mmol) were stirred in acetonitrile (50 mL).Tris(8-methylcarbonylthio-2,2,6,6-tetramethylbenzo-[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(0.1286 g, 0.1407 mmol, Example 49) was added in solid form and thecolor of the solution became brownish. Na₂ S₂ O₄ (20 mL, sat.) was addedafter 60 minutes and the mixture was stirred 5 minutes before separationof the phases. The aqueous phase was extracted with diethyl ether (50mL), and the combined organic phase was dried (MgSO₄) and evaporated,yielding 0.105 g (0.1168 mmol, 83%) of the title compound.

¹ H NMR (CDCl₃, 300 MHz) δ: 5.42 (s, CH, ¹ H), 2.40 (s, CH₃, 9H), 1.53(s, C₁ H₃, 36H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 191.16, 141.20, 139.66, 118.35, 108.81,90.39, 31.01, 29.88, 25.34.

MS (Thermospray) M⁺ +23 (Na) 921.

EXAMPLE 62Tris(8-tertbutylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane##STR84##

NaI (0.185 g, 1.2342 mmol) and trimethylsilyl chloride (0.156 mL, 1.2336mmol) were stirred in acetonitrile (50 mL).Tris(8-tertbutylcarbonylthio-2,2,6,6-tetramethylbenzo-[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(0.220 g, 0.2056 mmol, Example 47) was added in solid form and the colorof the solution became brownish. Na₂ S₂ O₄ (20 mL, sat.) was added after60 minutes and the mixture was stirred 5 minutes before separation ofthe phases. The aqueous phase was extracted with diethyl ether (50 mL),and the combined organic phase was dried (MgSO₄) and evaporated,yielding 0.105 g (0.1168 mmol, 83%) of the title compound.Tris(8-tertbutylcarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane(0.205 g, 0.200 mmol, 97.3%).

¹ H NMR (CDCl₃, 300 MHz) δ: 5.42 (s, CH, ¹ H), 1.51 (s, CH₃, 36H), 1.29(s, CH₃, 27H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 200.51, 141.45, 139.68, 117.99, 108.59,90.78, 46.90, 31.03, 27.17, 25.34.

MS (Thermospray) M⁺ +23 (Na) 1047.

EXAMPLE 63Bis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl##STR85##

Bis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane(0.100 g, 0.136 mmol) (from Example 23) was dissolved in a mixture ofTHF (40 mL, Al₂ O₃) and DMSO (10 mL, mol. sieves.). tBuOK (0.0168 g,0.150 mmol) was added and the resulting mixture was heated to 75° C. for1 hour. The solution was dark green/black at this time. I₂ (0.038 g,0.150 mmol) was added and a sample was taken after 1 minute and anOverhauser enhancement experiment was done; a 19 times enhancement wasmeasured at 5 W irradiation (200 G, 548.9 MHz, THF). After dilution withether (100 mL), extraction with Na₂ S₂ O₃ (sat.40 mL), drying (Na₂ SO₄)and evaporation, an Overhauser enhancement of 50 at 5 W irradiation wasobtained.

ESR (200 G, 548.9 MHz, three lines, THF): Linewidth 85 mG, a_(H) 175 mG.

EXAMPLE 64Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl##STR86##

Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane(0.104 g, 0.134 mmol, Example 23) was dissolved in a mixture of DMSO (10mL), and diethyl ether (30 mL). NaH (0.0037 g, 0.134 mmol, 80% in oil)and KOtBu (catalytic amount) were added and the resulting mixture wasstirred under argon. Samples (about 50 mL) were taken with irregularintervals and quenched with DCl/D₂ O (10% DCl) under argon. After 2hours and 15 min. the ¹ H NMR measurements of the evaporated diethylether extact from the quench showed 37% deuteration (anion formation).18 Hours after the start the deuteration level was 70%. The calculatedamount left in the flask was 78 mg at this time. I₂ (0.056 g, 2equivalents) was added and the reaction mixture was worked up after 2minutes reaction time. The mixture was diluted with diethyl ether (50mL) and washed with Na₂ S₂ O₃ (sat. 2×25 mL), dried (Na₂ SO₄) andevaporated yielding 0.030 g (40.8%). The radical content was 60%according to ¹ H NMR (Evans method) and 64% by HPLC (Kromasil 10 mm, C8,250 mm long, i.d. 4.6 mm, CH₃ CN:H₂ O 70:30 to 100:0 gradient 20minutes, UV 254 nm detection).

Overhauser enhancements (200 G, 548.9 MHz, 5.9 mM in THF): 9 mW 51, 18mW 88, 5W 251.

The HPLC chromatogram of thetris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methylradical showed a peak at 5.93 s corresponding to the radical and a peakat 6.58 s corresponding to the starting material. The HPLC separatedmaterials also showed distinct UV spectra.

EXAMPLE 658-Mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)carboxylicacid ethylester ##STR87##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (4.00 g, 18.00mmol, Example 5) was dissolved in diethyl ether (50 mL, sodiumbenzophenone ketyl), n-butyl lithium (7.56 mL, 18.90 mmol, 2.5M inhexane) was added and the resulting solution was refluxed 30 minutes.More diethyl ether (30 mL) was added and the mixture was cooled to -70°C. and S₈ (0.5759 g, 17.96 mmol) was added and the temperature wasincreased to 0° C. THF (100 mL) was added 2 hours after increasing thetemperature and the mixture was recooled to -70° C. n-Butyl lithium(8.64 mL, 18.0 mmol) was added and the temperature was increased to 0°C. One hour and forty five minutes later the slurry was filtered througha glass sinter (no. 4) at one of the three necks of the reaction flask.The white crystals (lithium salt) were washed with diethyl ether (50 mL,sodium benzophenone ketyl) under argon, and the ether removed byfiltration through the sinter. Weighing of the flask with the drylithium salt indicated that there remained around 8 mmol lithium salt inthe flask. THF (70 mL) was added to the salt, the mixture cooled to 0°C., and diethyl carbonate (0.654 mL, 5.4 mmol) was cannulated into thesolution and the mixture was left overnight to reach room temperature.The mixture was diluted with ether (300 mL), extracted with NaH₂ PO₄buffer (2×50 mL, sat.), dried (MgSO₄) and evaporated yielding the titlecompound, 1.60 g (4.90 mmol, 90.7% relative to diethyl carbonate).

¹ H NMR (CDCl₃, 300 MHz) δ: 4.36 (k, CH2, 2H), 1.70 (s, CH₃, 12H), 1.35(t, CH₃, 3H).

MS (EI) M⁺ 326, 280, 224.

EXAMPLE 66 Tris(2-methoxycarbonylthien-4-yl)methane ##STR88##

Dry powdered AlCl₃ (47.12 g, 0.353 mol) was placed in a three-neckedflask and a mixture of thiophene-2-carboxylic acid methyl ester (20.0 g,0.141 mol) and chloroform (47.8 g, 32.3 ml, 0.40 mol) was added rapidlybut dropwise. After heating at reflux temperature for 1.5 h, the mixturewas hydrolyzed with 50% aqueous HCl (100 ml). Extraction with CH₂ Cl₂(3×150 ml) followed by drying of the combined organic phases (MgSO₄) andevaporation gave the crude product as a red solid. Filtering through ashort silica column using petroleum ether/EtOAc as the eluant, followedby evaporation gave the title compound as a light yellow solid. Yield:17.9 g (88%).

¹ H NMR (CDCl₃, 300 MHz) δ: 7.56 (CH, 3H, d, J=1.6 Hz), 7.12 (CH, 3H,m), 5.50 (CH, ¹ H, s), 3.84 (OCH₃, s, 9H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 162.31 (C═O), 143.79 (quart. C--CO₂ Me),134.56 (quart. C--CH), 133.59 (thienyl CH), 129.03 (thienyl CH), 52.08(OCH₃).

EXAMPLE 67 Tris(2-methoxycarbonylthien-4-yl)methyl ##STR89##

Tris(2-methoxycarbonylthien-4-yl)methane (0.218 g, 0.5 mmol, Example 66)was dissolved in dry THF (25 ml) under an argon atmosphere. Solid KOtBu(0.055 g, 0.5 mmol) was added, the solution was stirred for 30 min. andI₂ (0.127 g, 1.0 mmol) was added.

The Overhauser effect was measured directly on this solution and foundto be 4 at 5 W.

EXAMPLE 68Tris(8-methylsulfonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl]methyl##STR90##

Tris(8-methylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methyl(0.163 g, 0.20 mmol, approximately 15% radical content, Example 8) wasdissolved in CH₂ Cl₂ (10 ml) under an argon atmosphere and3-chloroperbenzoic acid (0.207 g, 1.20 mmol) was added. After stirringfor 15 minutes, ESR spectroscopy of the reaction mixture showed a newradical.

ESR: 6 lines with a_(H) : 290 mG, linewidth: 113 mG. Overhauserenhancement: 5 at 5 W.

EXAMPLE 69Bis(8-methyloxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(8-cyano-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR91##

The title compound was isolated as a byproduct in the synthesis oftris(8-methoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(Example 15) in a yield of about 5%.

¹ H NMR (CDCl₃, 300 MHz) δ: 3.84 (s, 6H), 1.50 (s, CH₃, 36H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 163.43, 141.70, 140.57, 139.29, 139.07,119.92, 118.50, 116.34, 114.52, 11.58, 99.30, 78.49, 72.51, 51.89,25.54, 25.48.

MS (EI) M⁺ 833.

IR (KBr, cm-1): 3000 (CH), 2240 (CN), 1760 (CO).

EXAMPLE 70Bis(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(1,2,3-trimethoxy-5-phenyl)methanol##STR92##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (2.22 g, 10.0 mmol(Example 5)) was dissolved in THF (50 mL, sodium benzophenone ketyl) andcooled to -20° C. n-Butyl lithium (4.80 mL, 12.0 mmol, 2.5M in toluene)was added and the temperature increased to ambient temperature. Themixture was recooled to -20° C. and 3,4,5-trimethoxybenzoic acid methylesther (1.13 g, 5.0 mmol) dissolved in THF (10 mL) was added and theresulting mixture was stirred at ambient temperature overnight. Thesolution was poured onto acidic water (2% AcOH, 50 mL) and extractedwith diethyl ether (2×50 mL). The organic phase was washed with water(2×50 mL), dried (Na₂ SO₄) and evaporated yielding 3.10 g (4.7 mmol,97%) of the title compound.

¹ H NMR (CDCl₃, 300 MHz) δ: 6.75 (s, arom. H, 2H), 6.28 (s, arom. H,2H), 3.83 (s, OCH₃, 3H), 3.76 (s, OCH₃, 6H), 1.44 (s, CH₃, 24H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 152.29, 140.33, 138.81, 138.25, 137.56,117.07, 113.58, 105.52, 92.06, 76.77, 60.86, 56.16, 25.30, 25.19.

MS (Thermospray): M⁺ +23 (Na) 661.

EXAMPLE 71Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl##STR93##

Tris(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxle-4-yl)methanol(0.050 g, 0.048 mmol (Example 27)), was dissolved in dry THF (20 mL).Under Ar (g) BF₃.OEt (0.020 mL, 0.080 mmol) was added, and an intenseblue color developed (formation of carbocation). After 1 h was added acomplex of Chelex-100 and SnCl₂ ⁺ i.e. Chelex-100-Sn₂ ⁺ [0.50 g, 0.05mequiv. of Sn²⁺ ; (Preparation of the Chelex-100-Sn+-complex: 20 g (58mequiv. of Na⁺) of Chelex-100 was treated with 14 g (of SnCl₂.H₂ O, 116mequiv.) in water (100 mL). The solid material was filtered and washedwith water (100 mL) and EtOH (500 mL) and ether (100 mL) and was thendried in a desiccator at 0.1 torr, yielding the dry complex (25 g).)],followed 15 min later by Zn dust (0.030 g, 0.450 mmol). The reactionmixture started to change to a brown color. The reaction mixtured wasdirectly filtered through a 3 cm (i.d. 1 cm) glass column filled withSiO₂ (Merck, 0.043-0.060 mm) eluting with diethyl ether. The eluate wasdried (Na₂ SO₄), filtered and the solvent was evaporated, yielding ablack crystalline mass (0.048 g, 95.8%).

Overhauser enhancement: 89 at 9 mW in THF at 1.84 mM, (concetrationestimated by NMR--Evans method).

ESR spectrum: 7 lines, Linewidth 31 mG, a_(H) =62 mG

EXAMPLE 72 1,2,4,5-Tetratrimethylsilyloxybenzene ##STR94##

1,2,4,5-Tetrahydroxybenzene (14.20 g, 100.0 mmol (Example 4)) wasdispersed in pyridine (100 mL) and diethyl ether (100 mL), and Me₃ SiCl(70 mL, 645 mmol) was slowly added (heat evolved). After 3 hours thepyridiniumchloride was filtered off and the solvents of the filtrate(red) were evaporated, leaving a red oil, which was dissolved in ether,more solid material was filtered off, and the solvents of the filtrate(red) were evaporated. The residue was dissolved in diethyl ether andextracted with water (2×50 mL). The organic layer was separated, dried(Na₂ SO₄), filtered and the solvent was evaporated and the residualcrystalline material was washed with cold MeOH, leaving white crystals(needles), which were dried in vacuum (4.6 g, 10%) melting at 112° C.GC/MS showed M⁺ 430 (100%)

¹ H NMR (CDCl₃, 300 MHz) δ: 6.32 (s, CH, 2H), 0.20 (s, Si(CH₃)₃ 36H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 140.17, 113.63, 000.15.

EXAMPLE 73Tris(8-nitroethenyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane##STR95##

Tris(8-nitromethylhydroxymethyl-2,2,6,6-tetramethylbenzo-[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane(0.670 g, 0.710 mmol (Example 83)) was dissolved in Ac₂ O (30 mL) andNaOAc (2.00 g, 24.4 mmol) was added and the reaction mixture wasrefluxed for 0.5 h. The solution turned deep red. The solvent wasevaporated and the residue was partitioned between ether (100 mL) andwater (50 mL). The organic layer was separated, dried (Na₂ SO₄),filtered and the solvent was evaporated yielding a deep red crystallineresidue (0.62 g, 98%). The ¹ H NMR and ¹³ C NMR spectra were inidentical to those recorded for the same product, given in Example 82.

EXAMPLE 74 3,4-Dihydroxy-2,5-thiophenyl dicarboxylic acid diethylester##STR96##

Sodium (27.8 g, 1.21 mol) was dissolved cautiously in refluxing absoluteEtOH (1300 mL) and a mixture of bis(ethoxycarbonylmethyl)sulfide (108.0g, 0.540 mol) and diethyl oxalate (81.8 g, 0.540 mol) was addeddropwise. The reaction mixture was refluxed for 1 hour, allowed to cool,filtered and acidified. The new precipitate was filtered and dried (80°C.) in vacuum. Recrystallization from EtOH:EtOAC (1:1) (450 mL) gave twocrops of the thiophene; 93.2 g (67%).

¹³ C NMR (DMSOd₆, 75 MHz) δ: 161.93, 150.15, 107.92, 60.80, 14.11.

EXAMPLE 75 3,4-Methylenedioxy-2,5-thiophenedicarboxylic aciddiethylester ##STR97##

3,4-Dihydroxy-2,5-thiophenyl dicarboxylic acid diethylester (68.4 g, 300mmol (Example 74)), bromochloromethane, K₂ CO₃ (40.0 g) and Na₂ S₂ O₄ (4spoons) were mixed in DMSO (315 mL) and refluxed for 24 h. The reactionmixture was filtered, cooled and filtered again. The solvent wasevaporated, leaving a solid residue which was dissolved in CH₂ Cl₂ andfiltered. The filtrate was washed with water, 10% NaHCO₃ and water. Theorganic layer was separated, dried (Na₂ SO₄), filtered and the solventwas evaporated, yielding a crystalline residue, which was recrystallizedfrom absolute EtOH (800 mL; the filtration performed while the solventwas hot), yielding the desired product3,4-methylenedioxy-2,5-thiophenedicarboxylic acid diethylester (11.8 g,15%), melting at 124° C.

¹³ C NMR (DMSOd₆, 75 MHz) δ: 160.13, 151.51, 113.36, 104.20, 61.87,14.46.

EXAMPLE 76 3,4-Methylenedioxy-2,5-thiophenedicarboxylic acidmonoethylester ##STR98##

3,4-Methylenedioxy-2,5-thiophenedicarboxylic acid diethylester (3.08 g,11.3 mmol (Example 75)) was refluxed in EtOH/KOH (88 mL EtOH and 5.57 g,11.3 mmol KOH) for 48 h. The reaction mixture was allowed to cool andthe precipitate was filtered and the filter cake was triturated withcold 0.1M HCl. The basic filtrate from the first filtration was alsotriturated with 0.1M HCl and the crystals from these acidifications werepooled, dried and later recrystallized from water/EtOH (1:1) and yielded2.62 g (95%) of the desired mono-carboxylic acid.

¹³ C NMR (DMSOd₆, 75 MHz) δ: 161.11, 159.83, 151.07, 150.64, 112.65,105.43, 103.39, 61.35, 14.07.

EXAMPLE 77 3,4-Methylenedioxy-2-bromo-5-ethoxycarbonyl thiophene##STR99##

(See Chem. Ber. 108 (1975) p.576).3,4-Methylenedioxy-2,5-thiophenedicarboxylic acid monoethylester (5.00g, 20.5 mmol (Example 76)) was dissolved in water (115 mL) and thesolution was made alkaline to pH 11 with K₂ CO₃. The solution wasfiltered and warmed to 50° C. before Br₂ (1.8 mL) was added during aperiod of 1 h. Crystals precipitated, the precipitate was filtered offand the filter cake was washed with water and dried, yielding 2.3 g(34%) of the desired product, melting at 93° C.

¹³ C NMR (DMSOd₆, 75 MHz) δ: 160.11, 150.32, 147.09, 110.75, 102.96,85.64, 6.45, 14.33.

EXAMPLE 78 3,4-Methylenedioxy-2-bromo-5-carboxy thiophene ##STR100##

NaOH (10%) and MeOH were mixed in the proportion 1:1 (80 mL) and addedto 3,4-methylenedioxy-2-bromo-5-ethoxycarbonyl thiophene (1.91 g, 7.00mmol (Example 77)), and the reaction mixture was heated to 60°-70° C.and kept there for 2 h. After cooling, the reaction mixture was filteredand the MeOH of the filtrate was evaporated and water was added.Acidification with 10% HCl precipitated the free acid3,4-methylenedioxy-2-bromo-5-carboxy thiophene, which was filtered anddried in a desiccator (P₂ O₅), yielding 1.41 g (82%).

MS (EI 70 ev): M⁺ 324 and 322 of the TMS derivative.

EXAMPLE 79 3,4-Methylenedioxy-2-bromo-thiophene-5-carboxylic acidchloride ##STR101##

3,4-Methylenedioxy-2-bromo-5-carboxy thiophene (9.64 g, 38.4 mmol(Example 78)) was dissolved in dry DMF (0.73 mL) and SOCl₂ (38 mL) wasadded and the reaction mixture was refluxed for 5 hours. Excess SOCl₂was removed by distillation under reduced pressure, yielding 9.75 g(94%) of the acid chloride, which was used in the next reaction (seeExample 80) without further purification.

EXAMPLE 80 ##STR102##

The crude 3,4-methylenedioxy-2-bromo-thiophene-5-carboxylic acidchloride from Example 79 (0.398 mmol) was dissolved in CH₂ Cl₂ (1.0 mL)and slowly added dropwise to a mixture of 2-amino-2-methyl-1-propanol(0.478 mmol) and 4,4-dimethylamino pyridine (0.059 g, 0.478 mmol) in CH₂Cl₂ (1.0 mL) at 0° C. After 12 h at room temperature water (2 mL) wasadded and the organic phase was separated and washed with two moreportions of water (2×2 mL). The organic phase was dried by passing itthrough a small pipette packed with ground CaCl₂ and evaporated yielding0.1286 g (85%).

GC/MS on the TMS derivative showed (M⁺ -TMS+H) at m/e 321/323(containing Br).

EXAMPLE 81 ##STR103##

The product of Example 80 (0.100 g, 0.370 mmol) was dissolved in CH₂ Cl₂and chilled to 0° C. and molecular sieves (3 Å, dried at 350° C. invacuum) were added before adding SOCl₂ (740 mmol). The reaction mixturewas stirred at room temperature over night. Excess solvent and SOCl₂were removed under reduced pressure and the residue was partitionedbetween 10% Na₂ CO₃ and CH₂ Cl₂. The organic phase was separated, dried(Na₂ SO₄), filtered and the solvent was evaporated yielding 0.050 g(44%) of the desired product.

GC/MS on the TMS derivative showed M⁺ at 303/305 (containing Br).

EXAMPLE 82Tris(8-nitroethenyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane##STR104##

Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methan(0.45 g, 0.59 mmol, (Example 23)), nitromethane (20 mL, 290 mmol) andammonium acetate (0.12 g, 1.56 mmol) were mixed and heated to 100° C.for 6.5 h. After cooling, water (70 mL) was added, followed by ether(100 mL). The organic phase was separated, dried (Na₂ SO₄) and thesolvents evaporated, leaving a dark-red oil, which solidified after pumpdrying, yielding 0.38 g (72%) of the product.

¹ H NMR (CDCl₃, 300 MHz) δ: 7.98 (d, CH--NO₂, ¹ H, JHH 11 Hz) 7.80 (d,CH, ¹ H, JHH 11 Hz), 5.41 (s, CH, ¹ H), 1.54 (s, CH₃, 36H ).

¹³ C NMR (CDCl₃, 300 MHz) d:137.10, 136.86, 136.01, 126.29, 116.63,107.32, 95.42, 68.89, 22.78.

MS (EI): M⁺ +1 891 (40%), M⁺ 890 (75%), 818 (100%).

EXAMPLE 83Tris(8-nitromethylhydroxymethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methane##STR105##

Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methane(0.150 g, 0.197 mmol, Example 23) and nitromethane (0.36 g, 5.9 mmol )were mixed in dry dioxane (20 mL), and NaH (0.030 g, 0.197 mmol, 80% inoil) was added at ambient temperature. After stirring overnight, thereaction was checked by TLC, and found to be completed. IR (film onNaCl) of the reaction mixture confirmed this, no CHO fragment coud bedetected. Water (50 mL) and a few drops of HCl (2M) were added. Themixture was extracted with ether (3×50 mL). The organic extracts werewashed with water (40 mL), dried (Na₂ SO₄) and the solvent wasevaporated, leaving a crystalline yellow residue. The product waschromatographed on a column of silica with CH₂ Cl₂,EtOAc 45:5 as eluent.The fractions containing pure product were pooled and the solvent wasevaporated, yielding 0.150 g (81%).

¹ H NMR (CDCl₃, 300 MHz) δ: 5.40-5.50 (m, CH--O, ¹ H), 5.36 (s, CH, ¹H), 4.79-4.86 (m, CH₂ NO₂, ¹ H), 4.61-4.66 (m, CH₂ --NO₂, ¹ H), 3.07 (s,OH, ¹ H), 1.50 (s, CH₃).

¹³ C NMR (CDCl₃, 75 MHz) δ: 139.87, 137.08, 118.38, 118.21, 78.80,64.94, 30.58, 25.36 and 25.30 (CH₃, two resonances due to assymmetry).

EXAMPLE 84Tris(8-diethylaminocarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methyl##STR106##

Tris(8-diethylaminocarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methane(0.076 g, 0.080 mmol (Example 87)) was dissolved in a mixture of of dryTHF (40 mL, sodium benzophenone ketyl) and dry DMSO (10 mL, molecularsieves 4 Å) under N₂. KOtBu (0.009 g, 0.080 mmol) was added and themixture stirred at room temperature for 4 hours.

n-BuLi (0.1 mL, 2.5M in toluene, 0.25 mmol) was added, and the colour ofthe reaction mixture changed to dark red, after which I₂ (0.041 g, 0.16mmol) was added. A sample of this solution was investigated by ESRspectroscopy, indicating a radical content of <5% Overhauser enhancement2-10 at 2 W.

EXAMPLE 85Tris(8-methylthiobenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol andtris(8-methylthiobenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl.##STR107##

Tris(benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol (1.00 g, 1.90 mmol(Example 3) was mixed with dry THF (25 mL, sodium benzophenone ketyl)under Ar (g) and cooled to -78° C. n-BuLi (3.8 mL, 2.5M solution inhexane) was added with a syringe. The cooling bath was removed and theresulting mixture was allowed to reach room temperature. The mixtureturned thick and pasty and THF (25 mL, sodium benzophenone ketyl) wasadded in order to facilitate stirring. After 1 day CH₃ SSCH₃ (1 mL) wasadded. The mixture became homogeneous (and dark) almost instantaneously.After 2 hours, the reaction mixture was poured on ice-water (200 mL) andextracted with CH₂ Cl₂ (3×100 mL). The organic phase was dried (MgSO₄)and filtered and the solvent was evaporated to give a dark brown syrup,which was dissolved in CHCl₃, filtered through SiO₂ and evaporated to anew syrup. The brown syrup was chromatographed on SiO₂ with Et₂ O aseluent. (The sample was applied to the column in a mixture of Et₂ O/CH₂Cl₂). Yield 1.05 g, 84%. MS (EI 70 ev): M⁺ +662, 646, 616, 570.Tris(8-methylthiobenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol wasconverted to the corresponding radical with BF₃.OEt₃ (cation formation)and CrCl₂ (reductant) as described in other Examples. The ESR spectrumshowed a linewidth of 120 mG in THF at a concentration of 1 mM. TheOverhauser enhancement was 10 at 5 W.

EXAMPLE 862,6-Disilicium-2,2,6,6-tetra-tert-butylbenzo[1,2-d:4,5-d']'bis(1.3)dioxole##STR108##

1,2,4,5-Tetrahydroxybenzene (0.284 g, 2.0 mmol (Example 4)) andimidazole (0.81 g, 12.0 mmol) were dissolved in dry DMF (15 ml) anddi-t-butyldichlorosilane (1.28 g, 6.0 mmol) was added dropwise withstirring. The solution was stirred for 15 h, diethyl ether (50 ml,sodiumbenzophenone ketyl) was added. The organic phase was washed with HCl(2×25 ml, 5%), NaOH 2×25 ml, 1M), water (25 ml), dried and evorporated,yielding 0.50 g of a solid yellow residue. Recrystallization fromdiisopropyl ether gave 0.330 g (39%) pure, slightly yellow compound.

¹ H NMR (CDCl₃, 300 MHz) δ: 6.12 (s, CH, 2H), 1.05 (s, bu, 36H).

MS (EI, 70 ev, GLC inlet) m/e: 425 (3), 424 (12), 423 (36), 422 (100),383 (14), 382 (31)

EXAMPLE 87Tris(8-diethylaminocarbonyl-2,2,6,6-tetramethylbenzo[1.2-d:4,5-d']'bis(1.3)dioxole-4-yl)methaneandbis(8-diethylaminocarbonyl-2,2,6,6,-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane##STR109##

A crude mixture oftris(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methaneandbis(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)mono(2,2,6,6,-tetramethylbenzo[1,2-d:5-d']bis(1,3)dioxole-4-yl)methane(1.00 g, from Example 18) was dissolved in dry THF (10 mL) at roomtemperature, SOCl₂ (0.61 mL, 8.4 mmol) was added, and stirring wascontinued for 2.5 hours. The solvent and excess SOCl₂ was evaporatedunder reduced pressure, leaving a brown crystalline residue, which wasdried on a vacuum pump (<1 torr) for 10 h. This residue was dissolved indry THF (5 mL), and Et₂ NH (1.50 g, 21.0 mmol) was added and stirred for12 hours. The reaction mixture was partitioned between ether (75 mL) andwater (50 mL). The organic phase was separated, dried (Na₂ SO₄),filtered and the solvent was evaporated leaving a brown crystallineresidue. Chromatograhpic (RP8, 10 μm, 20×250 mm, CH₃ CN:H₂ O 75:25)separation, yielded 0.100 g (0.098 mmol, 14%) oftris(8-diethylaminocarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methaneand 0.150 g (160 mmol, 37%) ofbis(8-diethylaminocarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane.The yields are calculated for two steps (including the reaction inExample 18).Tris(8-diethylaminocarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methane:

¹ H NMR (300 MHz. CDCl₃) δ: 1.06-1.12 (t, CH₃. 3H), 1.17-1.24 (t, CH₃.3H), 1.52 (s, CH₃, 36H), 3.26-3.37 (q, CH₂, 2N), 3.51-3.60 (q, CH₂. 2H),5.41 (s, CH, 1H).Bis(8-diethylaminocarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bos(1,3)dioxole-4-yl)methane

¹ H NMR (300 MHz. CDCl₃) δ: 1.06-1.12 (t, CH₃. 3H), 1.17-1.24 (t, CH₃.3H), 1.52 (s, CH₃, 24H), 1.54 (s, CH₃, 12H), 3.26-3.37 (q, CH₂. 2H),3.51-3.60 (qs, CH₂, 2H), 5.41 (s, CH, 1H), 6.21 (s, aromatic H, 1H).

EXAMPLE 88Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methylbisulfite adduct ##STR110##

Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methyl(0.065 g, 0.976 mmol (Example 64)), with a radical content of about 10%,and Na₂ S₂ O₅ (0.370 g, 1.95 mmol) were mixed in a 25 mL round flaskunder N₂ (g). Water (1.5 mL, He degassed 15 min.) and dioxane (1.5 mL,He degassed 15 min.) were added. After 15 minutes stirring most of thesolid material had dissolved. HPLC analysis showed that the startingaldehyde was consumed after 45 minutes. An Overhauser experimentconfirmed the presence of radical in the reaction mixture. Overhauserenhancement was 59 at 5 W microwave power. ESR four lines, Linewidth 133mG, a_(H) 973 mG.

The bisulfite adduct was precipitated by the addition of dioxane and theprecipitate was filtered and washed twice with dioxane. The product wasdried under vacuum in room temperature overnight.

EXAMPLE 89Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanebisulfite adduct ##STR111##

This reaction was performed withtris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methane(0.050 g, 0.066 mmol (Example 23)), and Na₂ S₂ O₅ (0.285 g, 1.5 mmol)analogous to the formation of the bisulfite adduct oftris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methylradical as detailed above in Example 88, yielding 0.140 g (thetheoretical yield is 0.070 g) of crystals containing NaHSO₃.

¹ H NMR (300 MHz, D₂ O) δ: 1.4 (d, CH₃, 36H), 5.2 (s, CH, ¹ H), 5.3 (s,CH--OH, 3H).

¹³ C NMR (75 MHz, D₂ O) d: 24.4 (d, CH₃), 28.0 (s, CH), 102 (s), 107(s), 119 (s), 138 (s), 140 (s), 164 (s)

EXAMPLE 90 Tris(4-carboxy-2,3,5,6-tetrachlorophen-1-yl)methyl ##STR112##

Tris(4-carboxy-2,3,5,6-tetrachlorophen-1-yl)methane (0.690 g, 0.87 mmol)[(1R (KBr, cm⁻¹) 3450 (O--H str.), 2920 (C--H str), 1720 (C═O str.),1550, 1420 (C--C in chlorinated aryls). ¹ H NMR (CD₃ OD, 300 MHz) δ:8.00 (s, CH, ¹ H), ¹³ C NMR (CD₃ OD, 75 MHz)) δ: 164.35, 132.40, 132.26,133.00. 132.00, 56.88.] was mixed with NaOH (s) (0.090 g, 3.6 mmol) inDMSO (10 mL) and stirred for 24 hours in the dark. I₂ (0.110 g, 0.43mmol) was dissolved in ether (40 mL) and this solution was added and theresulting mixture was stirred for 15 minutes. The reaction mixture waspoured on saturated NaHCO₃ (100 mL). The phases were separated and theaqueous phase (pH 2) was acidified to pH 1-2 (conc. HCl). The acidicaqueous phase was extracted with ether (2×100 mL). The ether phase werecombined, dried (Na₂ SO₄), filtered and the solvent was evaporatedyielding a tan semi-crystalline residue of 0.250 g (36%).

ESR (200 G): One line, Linewidth 570 mG. Overhauser enhancements (0.2Min H₂ O, 200 G, 548.9 MHz) 2-10 at 2 w microwave power.

EXAMPLE 91 Tris(4-trichloromethyl-2,3,5,6-tetrachlorophen-1-yl)methyl##STR113##

Tris(4-trichloromethyl-2,3,5,6-tetrachlorophen-1-yl)methane wasconverted to the corresponding radical as described in Example 90.

ESR (200 G): One line, Linewidth 1500 mG. Overhauser enhancements (200G, 548.9 MHz) 2-10 at 2 W microwave power.

EXAMPLE 92 Tris(2,3,5,6-tetrachloro-4-methylphen-1-yl)methyl ##STR114##

Tris(2,3,5,6-tetrachloro-4-methylphen-1-yl)methane was converted to thecorresponding radical as described in Example 90.

ESR (200 G): One line, Linewidth 3200 mG. Overhauser enhancements (200G, 548.9 MHz) 2-10 at 2 W microwave power.

EXAMPLE 93 (Phenyl)-(pyrid-4-yl)-(thien-2-yl)methanol ##STR115##

Thiophene (1.150 g, 13.60 mmol) was dissolved in diethyl ether (50 mL,sodium benzophenone ketyl) under argon. n-Butyl lithium (5.10 mL, 13.60mmol) was added quickly with a syringe under evolution of heat. Theresulting mixture was stirred for 1 hour and 15 minutes at roomtemperature. After cooling to -75° C., benzoylpyridine (2.50 g, 13.6mmol) dissolved in THF (10 mL) was added over a period of 10 minutes andthe resulting mixture was stirred for 60 hours at room temperature. Theresulting thick yellow suspension was diluted with THF (100 mL) and NaH₂PO₄ buffer (1.25M, 100 mL) was added. The organic layer was separatedand washed with more NaH₂ PO₄ buffer (2×30 mL, 1.25M), dried (Na₂ SO₄)and evaporated yielding 3.24 g of crude material. Chromatography (flash,TLC gel 125 g, CH₂ Cl₂ :diethyl ether 4:6) yielded 1.83 g (6.85 mmol,50%) of the title compound.

¹ H NMR (DMSO d₆, 300 MHz) δ: 8.49 (m, H), 7.49-7.47 (q, 1H), 7.35-7.24(m, 7H), 6.97-6.95 (q, 1H), 6.70-6.68 (q, 1H).

¹³ C NMR (DMSO d₆, 75 MHz) δ: 155.63, 151.55, 149.29, 146.14, 127.85,127.42, 127.00, 126.48, 126.44, 125.96, 121.89, 77.97.

MS (EI 70 eV): M⁺ +1 268, 190.

EXAMPLE 94 (m-Chlorophenyl)-(phenyl)-pyrid-4-yl)methanol ##STR116##

m-Chlorobromobenzene (2.60 g, 13.60 mmol) was dissolved in THF (50 mL,sodium benzophenone ketyl) under argon. The solution was cooled to -78°C. and s-butyl lithium (9.7 mL, 13.60mmol in cyclohexane/isopentane) wasadded over a period of 10 minutes. The resulting mixture was stirred for1 hour at -78° C. Benzoylpyridine (2.50 g, 13.6 mmol) dissolved in THF(10 mL) was added over a period of 5 minutes and the resulting mixturewas stirred for 60 hours at room temperature. The resulting yellowsolution was hydrolysed with NaH₂ PO₄ buffer (1.25M, 40 mL). The organiclayer was separated and washed with more NaH₂ PO₄ buffer (30 mL, 1.25M),dried (Na₂ SO₄) and evaporated. The solid was stirred with CH₃ CN (100mL) for 3 hours. The solid was filtered and dried and was shown by TLCand MS to be pure.

¹ H NMR (DMSOd₃, 300 MHz) δ: 8.52-8.50 (q, CH pyridine 2H), 7.35-7.09(m, 1H).

¹³ C NMR (DMSOd₃, 75 MHz) δ: 155.20, 149.37, 148.88, 145.68, 132.76,129.77, 127.99, 127.58, 127.37, 127.24, 127.16, 126.52, 122.52, 79.64.

MS (EI 70 eV): M⁺ +1 296 and 298, 218, 220.

EXAMPLE 95Tris(8-dimethylaminocarbonylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)-dioxole-4-yl)methane##STR117##

NaI (1.135 g, 8.00 mmol) and Me₃ SiCl (1 mL, 8.0 mmol) were stirred inCH₃ CN (70 mL) at 0° C.Tris(8-dimethylaminocarbonylthio-2,2,6,6-tetramethylbenzo-[1,2-d:4,5-d']bis(1,3)-dioxole-4-yl)methanol(1.00 g, 0.9979 mmol (Example 43)) dissolved in CH₃ CN 10 mL) was addedand the resulting solution stirred for 30 minutes when 1H NMR analysisof a small sample showed conversion to be complete. Na₂ S₂ O₃ (sat., 30mL) was added and the two phase system was stirred 30 minutes when moreNa₂ S₂ O₃ (sat. 30 mL) was added and the stirring was continued for 5more minutes. The phases were separated and the organic layer was dried(MgSO₄), filtered, the filter washed with diethyl ether (30 mL) and thesolution was evaporated, yielding 1.16 g yellow to brown crystals. Thecrystals were dissolved in CH₂ Cl₂, the solution was washed with NaHCO₃(30 mL, sat.) and H₂ O (30 mL), dried (MgSO4) and evaporated yielding0.92 g of the pure title compound.

¹ H NMR (CDCl₃, 300 MHz) δ: 5.38 (s, 1H) 3.04 (s, 9H), 2.94 (s, 9H),1.51 (s, 36H).

13C NMR (CDCl₃, 75 MHz) δ: 163.22, 142.11, 139.50, 117.93, 108.75,90.79, 36.91, 30.96, 25.30.

MS (Thermospray): M⁺ +18 1003.

EXAMPLE 96Bis(8-methylmercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2-methylmercaptopyrimidin-5-yl)methyl##STR118##

Bis(8-methylmercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2methylmercaptopyrimidin-5-yl)methanol(0.075 g, 0.109 mmol (Example 60)) was dissolved in THF (75 mL, sodiumbenzophenone ketyl). BF₃.OEt₂ (0.475 mL, 1.853 mmol, 48% in diethylether) was added. The color changed from yellow to green. The solutionwas stirred for 15 minutes and SnCl₂ (0.103 g, 0.545 mmol) was added. 30minutes later Zn (0.178 g, 2.725 mmol) was added and there followed animmediate color change to yellow/brown/greyish. More Zn (0.230 g, 3.51mmol) was added one hour after the first addition. After leeting the Znsettle, a sample was taken with a gas tight syringe and an Overhauserenhancement experiment was performed on this solution. The measuredenhancement was 100 at 5W microwave power.

EXAMPLE 97Bis(8-methoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(8-ethoxycarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR119##

The title product was isolated by HPLC as a by product from the reactiondescribed in Example 12.

¹³ C NMR (CDCl₃, 75 MHz) δ: 169.50, 168.99, 141.33, 141.28, 138.64,138.62, 117.77, 117.75, 112.53, 112.33, 96.66, 96.46, 72.48, 52.30,35.45, 35.40, 25.42.

EXAMPLE 98Bis(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(8-methoxycarbonylmethyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR120##

The title product was isolated by HPLC as a by product from the reactiondescribed in Example 12.

¹³ C NMR (CDCl₃, 75 MHz) δ: 169.52, 141.25, 140.13, 138.79, 138.68,117.66, 116.95, 112.73, 111.90, 96.46, 96.34, 72.53, 35.36, 25.39,25.34.

EXAMPLE 99 Tris(benzothien-2-yl)methanol ##STR121##

Benzothiophene (5.42 g, 0.0382 mmol) was dissolved in diethyl ether (100mL). n-Butyl lithium (20.0 mL, 2M) was added at -15° C. under an argonatmosphere. The resulting mixture was allowed to reach room temperatureand diethyl carbonate (1.54 mL) was added and when TLC showed thereaction to be complete. The mixture was worked up by adding Na₂ HPO₄buffer (100 mL, sat.), separating the phases and washing the organicphase with more buffer and water. Drying (MgSO₄), evaporation andchromatographic separation yielded 1.40 g (25.7%) of the title compound.

¹³ C NMR (CDCl₃, 75 MHz) δ: 150.12, 140.08, 139.03, 124.48, 124.08,123.44, 122.37, 50.80.

EXAMPLE 1004-Allylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole##STR122##

The title product was synthesized from2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole (4.5 g, 0.02 mmol(Example 5)), n-butyl lithium (9.0 mL, 2.5M), S₈ (0.70 g) andallylbromide (2.42 g, 1.73 mL) in THF. Yield 4.9 g (83%) of a yellowbrown oil.

¹³ C NMR (CDCl₃, 75 MHz) δ: 141.82, 139.90, 133.76, 118.25, 117.38,98.31, 92.72, 36.66, 25.56.

EXAMPLE 101Tris(8-di(methylcarbonyloxyethyl)aminocarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)-dioxole-4-yl)methyl##STR123##

Tris(8-di(methylcarbonyloxyethyl)aminocarbonylmethylthio-2,2,6,6-tetramethylbenzo-[1,2-d:4,5-d']bis(1,3)-dioxole-4-yl)methanol(0.098 g, 0.066 mmol (Example 38)) was dissolved in THF (30 mL, Al₂ O₃).BF₃.OEt₂ (3.00 mL, 11.77 mmol, 48% in diethyl ether) was added. Thesolution was stirred for 30 minutes and SnCl₂ (0.159 g, 1.122 mmol) wasadded. 30 minutes later Zn (0.108 g) was added and there followed animmediate color change from blue to brown. After letting the Zn settle,a sample was taken with a gas tight syringe and an Overhauserenhancement experiment was performed on this solution. The measuredenhancement was 28 at 4 mW microwave power and 69 at 0.77 W.

ESR (200 G, THF solution): One line, linewidth 187 mG.

EXAMPLE 103 ##STR124##

The bromo oxazolidine thiophene of Example 81 is trimerized to thecorresponding trityl by treatment with one equivalent of n-butyl lithiumin THF at -75° C. for 30 minutes. 0.3 equivalents of diethyl carbonateis added at this temperature and the solution is allowed to reach roomtemperature over a period of several hours. The reaction mixture isworked up by pouring the solution on cold NH₄ Cl or cold Na₂ HPO₄ bufferfollowed by extraction with diethyl ether or CH₂ Cl₂. The organic phaseis washed with water, dried (Na₂ SO₄) and is evaporated to yield thecrude carbinol. The pure compound is obtained by chromatography oneither SiO₂ or RP₈ gel. The product is characterised by ¹ H NMR and ¹³ CNMR as well as other spectroscopic methods. The methanol compound iseither converted directly to the radical or first to the methane.

EXAMPLE 104Bis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)ketone##STR125##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole (8.88 g, 0.040mol (Example 5)) was dissolved in THF (250 mL) and cooled to -20° C.under a N₂ atmosphere. n-Butyl lithium (19.2 mL, 2.5M in toluene) wasadded and the temperature was allowed to increase to +10° C. over aperiod of 10 minutes. The mixture was then cooled to -20° C. and DMF(2.92 g, 0.040 mol) was added and the temperature was allowed to reachroom temperature in 2 hours. The mixture was again cooled to -20° C. anda second portion of n-butyl lithium (19.2 mL, 2.5M in toluene) wasadded. The temperature was allowed to reach room temperature in 1 hour.After once again recooling to -20° C., dimethyl carbonate (1.19 g,0.0132 mol) was added and the temperature was allowed to reach roomtemperature overnight. Water (300 mL) and acetic acid (2 mL) were addedand the solution was extracted with ether (3×150 mL). The organicextracts were combined, dried (Na₂ SO₄ and K₂ CO₃) and the solventevaporated leaving a semi-crystalline dark residue. The residue wascrystallized twice from EtOAc:heptane 4:1 giving the title compound as adeep red crystalline product. Yield 3.0 g (43%).

¹ H NMR (CDCl₃, 300 MHz) δ: 10.11 (s, CHO, 2H), 1.68 (s, CH₃, 24H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 185.25, 183.05, 141.08, 139.72, 121.48,112.12, 108.09, 25.72.

IR (KBr): 1700 (vs, C═) in CHO, 1670 (s, C═O).

EXAMPLE 105Tris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methanolandbis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-mono(2,2,6,6-tetramethylbenzo[1,2-di:4,5-d']bis-(1,3)dioxole-4-yl)methanolandmono(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-bis(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR126##

Tris(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)methanol(10.0 g, 0.0145 mol (Example 44)) was suspended in dry diethyl ether(300 mL). n-butyl lithium (29 mL, 0.0725 mol, 2.5M in hexane) was added,under nitrogen, and the solution was heated slowly to reflux temperature(ca. 20 min.). A second portion of n-butyl lithium (9.8 mL, 2.5M inhexane) was added and the heating was disrupted. 5 minutes after removalof the oil bath, DMF (130 mL, 0.169 mol) was added carefully. Theresulting mixture was stirred at room temperature over night. Water (300mL) and AcOH was (5 mL) was added to the solution. An orange colourappeared in the solution at this time. The mixture was extracted withdiethyl ether (2×300 mL). The combined organic phase was washed withwather (3×100 mL), dried (Na₂ SO₄, K₂ CO₃), treated with charcoal andfiltered through SiO₂ (3 cm, i.d. 5 cm) and evaporated. The residualbrown residue was dried under vacuum to leave a form weighing 11.1 g.This material was chromatographed on several columns of SiO₂ with CH₂Cl₂ :EtOAc 45:5 as eluent.

Yield oftris(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol1.8 g (16.9%).

¹ H NMR (CDCl₃, 300 MHz) δ: 10.08 (s, CHO, 3H), 4.32 (s, OH, 1H), 1.55(s, CH₃, 36H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 185.41, 140.82, 139.25, 119.58, 116.58,105.76, 72.71, 25.62.

MS (Thermospray): M⁺ +23 (Na) 799.

Yield ofbis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis-(1,3)dioxole-4-yl)-mono(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol4.5 g (42%).

¹³ C NMR (CDCl₃, 75 MHz) δ: 185.51, 140.77, 140.31, 139.41, 138.62,119.34, 117.53, 117.19, 110.80, 105.59, 92.31, 72.70, 25.60, 25.44.

MS (Thermospray): M⁺ +23 (Na) 771.

Yield ofmono(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)-bis(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol2.1 g (20.1%).

¹³ C NMR (CDCl₃, 75 MHz) δ: 185.69, 140.73, 140.19, 139.57, 138.81,119.12, 118.58, 116.95, 111.67, 105.43, 91.98, 72.71, 25.59, 25.43.

MS (Thermospray): M⁺ +23 (Na) 743.

EXAMPLE 1064-Formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)-dioxole##STR127##

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']bis(1,3)-dioxole (20.0 g, 90 mmol(Example 5)) was dissolved in THF (300 mL) and cooled to -20° C. n-Butyllithium (38.0 mL), 2.5M in toluene, 100 mmol) was added and thetemperature was allowed to rise to 0° C. The mixture was recooled to-20° C. and DMF (6.9 mL, 90.0 mmol) was added. The reaction mixture wasstirred over night while allowing the temperature to increase to roomtemperature. Water (200 mL) and AcOH (5 mL) was added. The color changedfrom light yellow to strong orange. The mixture was extracted withdiethyl ether (3×300 mL) and the combined organic phase was washed withwater (2×100 mL), dried (Na₂ SO₄) and evaporated. The product wastrituated twice with petroleum ether and dried, yielding the pure titlecompound; 16.3 g (72%).

¹³ C NMR (CDCl₃, 75 MHz) δ: 185.51, 140.84, 140.81, 120.17, 106.38,98.26, 25.67.

EXAMPLE 107Bis(8-formylethyleneglycolacetal-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)-dioxole-4-yl)ketone##STR128##

Bis(8-formyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)-dioxole-4-yl)ketone(2.0 g, 3.80 mmol (Example 104)), ethyleneglycol (50 mL) andmethanesulfonic acid (0.01 mL) were mixed and stirred at roomtemperature over a weekend. TLC analysis (SiO₂ CH₂ Cl₂ :Et₂ O 4:1)indicated that the reaction was complete. Pyridine (0.5 mL) was addedand the reaction mixture was partitioned between diethyl ether (200 mL)and water (250 mL). The aquous phase was extracted with more ether(2×200 mL). The combined organic phase was washed with water (100 mL),dried (Na₂ SO₄) and filtered through Al₂ O₃ (2.5 cm, i.d. 2 cm). Thesolvent was evaporated leaving a yellow crystalline product. Yield 2.12g (90.9%).

¹ H NMR (CDCl₃, 300 MHZ) δ: 6.06 (s, O--CH--O, 2H), 4.19-4.14 (m, CH₂,4H), 4.02-3.97 (m, CH₂, 4H), 1.61 (s, CH₃, 24H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 184.06, 139.68, 138.93, 119.37, 109.27,108.82, 97.94, 65.73, 25.66.

EXAMPLE 108 Tris(2,5-dimethylthien-3-yl)methanol ##STR129##

2,5-Dimethyl-3-iodo-thiophene (see S. Gronowitz and R. Beselin, Arkivfor Kemi 21: 349-355 (1963)) (0.05 mol) was dissolved in diethyl ether(150 mL, dry) and n-butyl lithium (25.0 mL, 2.06M) was added at -78° C.under N₂ and stirred for 30 minutes. Diethyl carbonate (2.0 mL, 0.0166mol) in diethyl ether (3 mL, dry) was added and the mixture was stirredfor 30 minutes. The cooling bath was removed and the temperature wasallowed to reach +10° C. At this temperature the mixture was poured ontoice/water. The organic phase was separated and washed with water (2×50mL), dried (MgSO₄) and evaporated. The resulting oil was taken up inpetroleum ether. After cooling the product was filtered and washed witha little petroleum ether. Yield 41.6%, mp. 110°-111° C.

¹ H NMR (C₆ D₆, 300 MHz) δ: 6.46 (H4, 3H), 2.19 (s, CH₃, 9H), 2.03 (s,CH₃, 9H), 1.70 (COH, 1H).

MS (EI 70 eV): M⁺ -1 361.

MS (Thermospray): M⁺ -17 345.

EXAMPLE 109 Tris(2,5-dimethylthien-3-yl)methane ##STR130##

Tris(2,5-dimethylthien-3-yl)methanol (Example 108)) was converted totris(2,5-dimethylthien-3-yl)methane using Me₃ SiCl, CH₃ CN and NaI asdescribed in several previous Examples, e.g. 17, 61, 62 and 95. Yield67.8%, mp 143°-144° C.

¹ H NMR (CDCl₃, 300 MHz) δ: 6.28 (s, 3H), 5.07 (s, methane CH, 1H), 2.34(s, CH₃, 9H), 2.18 (s, CH₃, 9H).

EXAMPLE 110 Tris(2,5-dimethylthien-3-yl)methanol ##STR131##Tris(2,4,5-trimethylthien-3-yl)methanol ##STR132##Bis(2,5-dimethylthien-3-yl)-mono-(2,3-dimethyl-4-iodothien-5-yl)-methanol##STR133##Bis(2,5-dimethylthien-3-yl)-mono(2,5-di-t-butyl-thien-3-yl)-methanol##STR134##

The title carbinols were made according to the same general procedure:To a stirred solution of the corresponding mono- or diiodinatedthiophene (0.05 mol) in diethyl ether (150 mL, dry) was added n-butyllithium (25.0 mL, 2.06M) at -70° C. under N₂. The solution was stirredfor 30 minutes at this temperature. The appropriate ketone (see A.Wiersma and S. Gronowitz Acta Chem Scand 24: 2593-2611 (1970) and Ya L.Goldfarb and P. A. Konstantinov, Bull. Acad. Sci. USSR, Engl transl.,108 1959) (0.05 mol), dissolved in diethyl ether (150 mL), was added andthe resulting solution was stirred for 30 minutes at this temperature.The cooling bath was removed and when the reaction mixture had reached+10° C. the mixture was poured on ice and water. The workup was asdescribed in Example 108.

Tris(2,5-dimethylthien-3-yl)methanol

MS (Thermospray): M⁺ -17 345

Tris(2,4,5-trimethylthien-3-yl)methanol

Yield: 3.5%

MS (Thermospray): M⁺ -17 723

Bis(2,5-dimethylthien-3-yl)-mono-(2,3-dimethyl-4-iodothien-5-yl)-methanol

Yield: 13.3%

MS (Thermospray): M⁺ -17 471

Bis(2,5-dimethylthien-3-yl)-mono(2,5-di-t-butyl-thien-3-yl)-methanol

Yield: 5.6%

MS (Thermospray): M⁺ -17 429

EXAMPLE 111 (Phenyl)-(pyrid-4-yl)-(thien-2-yl)methane ##STR135##

NAI (2.27 g, 16.0 mmol) and Me₃ Sicl (2.02, 16.0 mmol) were stirred inCH₃ CN (70 mL) at 0° C. (Phenyl)-pyrid-4-yl-(thien-2-yl)methanol (0.534g, 2.00 mmol (Example 93)) was added at 0° C. and the resulting solutionwas stirred over night at room temperature. Na₂ S₂ O₃ (sat., 20 mL) wasadded and the two phase system was stirred 5 minutes. The phases wereseparated and the organic layer was dried (MgSO₄), filtered andevaporated. The resulting crystals were dissolved in CH₂ Cl₂ (30 mL),the solution was washed with NaHCO₃ (30 mL, sat.) and H₂ O (30 mL),dried (MgSO₄) and evaporated yielding 0.41 g which was recrystallized indiisopropyl ether giving 0.22 g (43.8%) of the pure title compound.

¹ H NMR (CDCl₃, 300 MHz) δ: 8.53 (m, 2H), 7.37-7.11 (m, 8H), 6.96 (q,1H), 6.71 (dt, 1H) 5.64 (broad s, 1H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 152.33, 149.91, 145.53, 141.98, 128.72,128.63, 127.23, 126.73, 126.71, 125.04, 123.89, 51.37.

EXAMPLE 112 Bis(thien-2-yl)-mono-(4-methoxyphenyl)methyl ##STR136##

The carbinol of Example 115 (0.140 g, 0.463 mmol) was dissolved in dry(Al₂ O₃ filtered and Ar (g) saturated) THF (30 mL) and BF₃.Et₂ O (1.12g, 7.87 mmol) was added and stirring was maintained 30 minutes whenSnCl₂ (0.437 g, 2.31 mmol) was added. After stirring for another 30minutes, Zn dust (0.756 g, 11.6 mmol) was added and the stirring wascontinued. 30 minutes after the Zn addition a sample was taken with agas tight syringe, after letting the Zn settle, and Overhausermeasurements showed some radical formation to have occurred.

EXAMPLE 113Tris(8-diethylaminocarbonylmethylthio-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR137##

Tris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(1.00 g, 1.269 mmol (Example 31)) was added to a solution consisting ofCH₃ CN (50 mL), K₂ CO₃ (5.0 g and BrCH₂ CONEt₂ (0.776 g, 4.0 mmol) madefrom BrCH₂ COBr and HNEt₂ in CH₂ Cl₂) at -5° C. under argon. The coolingbath was removed and the temperature increased to +23° C. A ¹ H NMRcontrol of a small sample 20 minutes after the removal showed completeconversion to have occurred. Diethyl ether (50 mL) was added and thesolution was filtered. The solvents were evaporated and the residual1.28 g of oily material was heated in diisopropyl ether (30 mL, 40° C.).The material did not dissolve but changed into crystalline form in thisprocess. Filtration and drying gave 0.96 g (67.0%) of the titlecompound.

¹ H NMR (CDCl₃, 300 MHz) δ: 4.16 (s, COH 1H), 3.36 (q, NCH₂ CH₃, 6H),3.32 (q, NCH₂ CH₃, 6H), 1.50 (s, CH₃, 36H), 1.18 (t, CH₃, 9H, 1.08 (t,CC₃, 9H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 166.92, 141.20, 138.63, 117.57, 112.21,97.18, 75.52, 42.44, 40.13, 35.97, 25.48, 14.30, 12.83.

EXAMPLE 114Tris(8-diethylaminocarbonylmethylthio-2,2,6,6-tetramethyl-benzo[1,2-d:4,5']bis(1,3)dioxole-4-yl)methyl##STR138##

Tris(8-diethylaminocarbonylmethylthio-2,2,6,6-tetramethylbenzo[1,2-d:4,5']bis(1,3)dioxole-4-yl)methanol(0.100 g, 0.0886 mmol) was dissolved in dry (Al₂ O₃ filtered and Ar (g)saturated) THF (30 mL) and BF₃.Et₂ O (0.214 g, 1.51 mmol) was added andthe color changed immediately from yellow to blue, and stirring wasmaintained during 30 minute. SnCl₂ was added (0.084 g, 0.443 mmol) andthe stirring was continued for one hour. Zn dust (0.145 g, 2.22 mmol)was added and one hour later another portion of Zn dust (0.124 g, 1.89mmol) was added. An experiment one later on a crude sample from thereaction mixture, after letting the Zn settle, showed a 108 foldOverhauser enhancement at 4 mW microwave power.

EXAMPLE 115 Bis(thien-2-yl)mono(4-methoxyphenyl)methanol ##STR139##

p-Bromo methoxybenzene (0.96 g, 5.2 mmol) was dissolved in THF (50 mL)and n-butyl lithium (2.08 mL, 2.5M in toluene) was added at -70° C. andstirred at this temperature for 10 minutes when the thienyl ketone (1.0g 5.2 mmol) (see JACS 74: 1733-36 (1952), JCS 1956, 698-705 and Receuil68: 24 (1949)) dissolved in THF (5 mL) was added. The temperature wasallowed to rise gradually to room temperature over night. The mixturewas hydrolysed with water (50 mL). Ether (150 mL) was added and thephases were separated, the aqueous phase was extracted with more ether(100 mL) and the combined organic phase was washed with water (70 mL),dried (MgSO₄) and the solvent evaporated leaving a semicrystalline blackresidue. The black residue was dissolved in hot heptane/EtOAc (3:1) andchromatographed on a column of alumina with heptane:EtOAc 3:1 as eluent.The product was isolated in a yield of 0.72 g (46.0%).

¹ H NMR (CDCl₃, 300 MHz) δ: 7.38 (d, armoatic H m to OCH₃, 2H, J 9 Hz),7.29 (q, thiophene H α to S, 2H, J 5.1 Hz, J 1.2 Hz), 6.95 (q, thiopheneH β to S, 2H, J 5.1 Hz, J 3.6 Hz), 6.86 (d, aromatic H o to OCH₃ 2H, J 9Hz), 6.85 (s, thiophene γ to S, 2H, J 3.6 Hz, J 1.2 Hz), 3.81 s. OCH₃,3H), 3.04 (s, OH, 1H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 159.04, 152.05, 138.36, 126.38, 126.37,125.60, 113.12, 77.65, 55.18.

MS (EI 70 eV): M⁺ 302 (10%), M⁺ -16 286 (100%), M⁺ -17 285 (90%).

EXAMPLE 116Tris(8-propargylthio-2,2,6,6-tetramethyl-benzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol##STR140##

Tris(8-mercapto-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis(1,3)dioxole-4-yl)methanol(0.400 g, 0.50761 mmol (Example 31)) was added to a solution consistingof CH₃ CN (50 mL), K₂ CO₃ (5.0 g) and BrCH₂ CCH (2.389 g, 2.284 mmol) at-5° C. under argon. The cooling bath was removed and the temperatureincreased to +23° C. A ¹ H NMR control of a small sample 20 minutesafter the removal showed conversion to be complete. Diethyl ether (50mL) was added and the solution was filtered. The solvents wereevaporated and the residual oil weighed 0.401 g (87%).

¹ H NMR (CDCl₃, 300 MHz) δ: 4.15 (s, 1H, OH), 3.51 (d, 6H, CH₂), 2.97(t, 3H, CCH), 1.47 (s, CH₃, 36H).

¹³ C NMR (CDCl₃, 75 MHz) δ: 141.35, 138.38, 11.49, 112.38, 96.31, 79.73,72.32, 70.80, 25.26, 21.55.

The product may be substituted at the alkyne hydrogen by lithiationfollowed by reaction with carbon dioxide or with R*Lv where R* is thegroup (e.g. an alkyl group) to be introduced and Lv is a leaving group.

EXAMPLE 117

The following known free radicals were tested for Overhauserenhancement:

    ______________________________________                                                                        Over-                                                                         hauser                                                                        enhance-                                      Radical                 Power   ment                                          ______________________________________                                         ##STR141##             37 mW  5 W                                                                             2  70                                        (See Bert et al JACS 54: 3250 (1932):                                         Dunnebacke et al Chem. Ber. [1989] 122 533;                                   Judeikis et al JACS [1961] 84, 1132;                                          Sinclair et al JACS [1968] 90, 5074.                                           ##STR142##             37 mW  5 W                                                                             6.5 107                                      (see Dunnebacke et al (supra))                                                 ##STR143##              5 W     7                                            (ESR Linewidth 250 mG)                                                        (See Anderson et al Acta. Chem. Scand.                                        (1962), 16, 1817-1818;                                                        Falle et al, Canad. J. Chem.                                                  (1986), 44 1387;                                                              Ziegier et al, Annalen (1927), 458,                                           248;                                                                          Allan et al, J.C.S. (1986), 440; and                                          Anderson et al, Acta. Chem. Scand,                                            (1962), 16, 1817).                                                             ##STR144##              5 W     3                                            (ESR linewidth 600 mG                                                         a.sub.H 1200 mG)                                                              (see Gomberg JACS [1900], 22, 757)                                            ______________________________________                                        Example 118                                                                    ##STR145##                                                                   The title compound was prepared following the reaction scheme:                 ##STR146##                                                                   (Example 5)                                                                    ##STR147##                                                                    ##STR148##                                                                    ##STR149##                                                                   ______________________________________                                    

The title compound showed Overhauser enhancements of 52 at 3.5 W and 2at 22 mW. The ESR spectrum showed a linewidth of 65 mG.

FORMULATION EXAMPLES Example I

Intravenous enhancement agent

An Overhauser MRI enhancement solution is prepared as follows:

The freeze dried radical e.g. that of Example 11 is dissolved inoxygen-free water containing sodium chloride to ensure isotonicity. ThepH of the solution is adjusted with tris buffer to pH 7.4. CaNa EDTA isadded to prevent metal catalyzed oxidation. Ascorbic acid is added as anantioxidant.

An injectable solution is prepared which contains:

    ______________________________________                                        Radical                70 mmol                                                Sodium chloride        q.s.                                                   Tris buffer            q. s.                                                  CaNa EDTA              0.1 mmol                                               Ascorbic acid          0.01 mmol                                              Aqua purificata    ad  500 ml                                                 ______________________________________                                    

Example II

Intravenous enhancement agent

An Overhauser MRI enhancement is prepared as follows:

The radical (e.g. that of Example 11) is dissolved in water containingNaCl, KCl, CaCl₂ and MgSO₄ in physiological ratios of the cations toensure isotonic solution. The pH of the solution is adjusted to pH 7.4with HCl, NaOH or tris buffer.

A small amount of iron(III) chloride is added to prevent reduction ofthe radical.

An injectable solution is prepared which contains:

    ______________________________________                                        Radical                50 mmol                                                Sodium chloride        q.s.                                                   KCl, CaCl.sub.2, MgSO.sub.4                                                                          q.s.                                                   Tris buffer            q.s.                                                   FeCl3                  0.01 mmol                                              Aqua purificata    ad  400 ml                                                 ______________________________________                                    

Example III

Oral Overhauser MRI enhancement agent for abdominal studies

A suspension for oral Overhauser MRI studies is prepared as follows:

A radical (e.g. that of Example 11) is added to a vigorously stirredsolution of hydroxyethylcellulose in water (pre-stirred for 2.5 h)containing CaNa EDTA to prevent metal-catalyzed oxidation. Aspartame anda solution of anis essence, and methyl and propyl parahydroxybenzoatesin ethanol are slowly added. The suspension is filled into a 700 mlbottle. The suspension contains 5 mmol radical.

    ______________________________________                                        Radical                   5 mmol                                              Hydroxyethylcellulose    7.9 g                                                Methyl parahydroxybenzoate                                                                             0.7 g                                                Propyl parahydroxybenzoate                                                                            0.14 g                                                Ethanol                   10 g                                                Aspartame                0.2 g                                                Anis essence             0.2 g                                                CaNa EDTA                0.1 mmol                                             Water    ad              700 ml                                               ______________________________________                                    

Example IV

Preparation of capsules containing an Overhauser MRI enhancement agentfor oral use

    ______________________________________                                        Radical (e.g. of Example 11)                                                                      300 mg                                                    Amylum may dis      q.s.                                                      ______________________________________                                    

The powders are mixed and filled into capsules. (Capsule size 0)

Example V

Liposomal Overhauser MRI enhancement agents for intravenousadministration

The radical (e.g. that of Example 11) is encapsulated in smallunilamellar vesicles according to the method described in EP-A-160552(Vestas).

The purified liposome dispersion is filled into 50 ml vials and freezedried. Each vial contains 1 mmol radical. The product is suspended in 30ml saline before administration.

Example VI

Low concentration intravenous enhancement medium

The enhancement media of Examples I and II are diluted, 1 part by volumewith 99 parts by volume of water for injections to produce more dilutecontrast media suitable for use with sensitive SQUID basedmagnetometers.

Still lower concentrations, e.g. at the 10-10-10-6M level, can beproduced by further dilution.

Example VII

Intravenous Overhauser MRI enhancement agent

An Overhauser enhancement solution is prepared as follows:

The radical (e.g. that of Example 11) is dissolved in water containingNaCl, KCl, CaCl₂, MgSO₄ in physiological ratio to ensure isotonicitysolution. The pH of the solution is adjusted to pH 7.4 with HCl, NaOH ortris buffer.

A small amount of iron(III) chloride is added to prevent reduction ofthe radical.

An injectable solution is prepared which contains:

    ______________________________________                                        Radical                50 mmol                                                Sodium chloride        q.s.                                                   KC1, CaCl2, MgSO4      q.s.                                                   Tris buffer            q.s.                                                   FeCl3                  0.01 mmol                                              Aqua purificata    ad  170 ml                                                 ______________________________________                                    

Example VIII

Intravenous Overhauser MRI enhancement agent

An Overhauser enhancement solution is prepared as follows:

The freeze dried radical (e.g. of Example 11) is dissolved inoxygen-free water. The pH of the solution is adjusted with tris bufferto pH 7.4. CaNa EDTA is added to prevent metal-catalyzed oxidation.Ascorbic acid is added as an antioxidant.

An injectable solution is prepared which contains:

    ______________________________________                                        Radical                70 mmol                                                Sodium Chloride        q.s.                                                   Tris buffer            q.s.                                                   CaNa EDTA              0.1 mmol                                               Ascorbic acid          0.01 mmol                                              Aqua purificata    ad  50 ml                                                  ______________________________________                                    

We claim:
 1. A radical compound of formula Ia

    .C(Ar.sup.12).sub.3                                        (Ia)

wherein: each Ar¹², which may be the same or different, represents a6-membered carbocyclic, at least one group Ar¹² being a group Ar¹ ; eachgroup Ar¹ represents a 6-membered ring optionally substituted at the orany ortho carbon by a group R¹, R², R³ or R⁴, at the or any meta carbonby a group R² or R³, and at any para carbon by a group R¹, R², R³ or R⁴,with the proviso that no more than two ring carbons are unsubstituted;each of R¹, R², R³ or R⁴, which may be the same or different,independently represents a group of formula --M, --XM, --XAr² or --Ar² ;M represents a water solubilizing group, each group X, which may be thesame or different, represents an oxygen or sulphur atom or a NH or CH₂group; Ar² represents a 5 to 10 membered aromatic ring optionallysubstituted by a solubilizing group M; or groups R¹ and/or R⁴ ondifferent Ar¹ groups may together represent bridging oxygen or sulphuratoms or NR⁵ or CR⁵ ₂ groups, where R⁵ represents a hydrogen atom or anoptionally hydroxylated, optionally aminated, optionally alkoxylated,optionally carboxylated alkyl, oxo-alkyl, alkenyl or alkaryl group; or,groups R² and R³ may also represent hydrogen atoms or alkyl groups; or,adjacent pairs of groups R¹, R², R³ or R⁴, together with the twointervening carbon atoms, may represent groups of formula ##STR150##where R⁶ represents a hydrogen atom, a hydroxyl group, an optionallyalkoxylated, optionally hydroxylated acyloxy or alkyl group or asolubilizing group M; Z represents an oxygen or sulphur atom or a groupNR⁵, CR⁷ ₂ or SiR₇ ² ; each R⁷, which may be the same or different,represents a hydrogen atom, an alkyl, hydroxyalkyl, carboxy,alkoxycarbonyl or carbamoyl group; or two R⁷ groups together with theatom to which they are bound represent a carbonyl group or a 5 to 8membered cycloalkylidene, mono- or di-oxacycloalkylidene, mono- ordi-azacycloalkylidene, or mono- or di-thiacycloalkylidene groupoptionally with the ring attachment carbon replaced by a silicon atom;or R⁷ where it is other than hydrogen, is optionally substituted by agroup R⁶ ;or a salt thereof.
 2. A compound of formula Ia as claimed inclaim 1 wherein the Ar¹ group or groups are of formula ##STR151## whereeach Y independently represents CH, CM, C--XM, C--Ar² or C--XAr² .
 3. Acompound of formula Ia as claimed in claim 1 wherein each group Ar¹² isa group Ar¹.
 4. A compound of formula Ia as claimed in claim 1 whereineach group Ar¹ carries two fused groups of formula ##STR152## wherein Xand Z are as defined in claim
 1. 5. A compound of formula Ia as claimedin claim 4 wherein each group Ar¹ carries two fused groups of formula##STR153## wherein each R⁷, which may be the same or different,represents a hydrogen atom, an alkyl, hydroxyalkyl, carboxy,alkoxycarbonyl or carbamoyl, or two R⁷ groups together with the atom towhich they are bound represent a carbonyl group or a 5 to 8 memberedcycloalkylidene, mono- or di-oxacycloalkylidene, mono- ordi-azacycloalkylidene, or mono- or di-thiacycloalkylidene groupoptionally with the ring attachment carbon replaced by a silicon atom,or R⁷, where it is other than hydrogen, is optionally substituted by agroup R⁶, wherein R⁶ represents a hydrogen atom, a optionallyhydroxylated acyloxy or alkyl group, or a solubilizing group M;or a saltthereof.
 6. A magnetic resonance imaging contrast enhancing compositioncomprising a physiologically tolerable inert carbon free radical offormula

    .C(Ar.sup.12).sub.3                                        (Ia)

wherein each Ar¹², which may be the same or different, represents a6-membered carboxylic, at least one group Ar¹² being a group Ar¹ asdefined in claim 1, together with at least one pharmacologicallyacceptable carrier or excipient.
 7. A compound of formula .C(Ar¹)₃,wherein each group Ar¹ is a group of formula ##STR154## wherein each R¹is a group M or XM, wherein M is a water solubilizing group, and X isoxygen, sulphur, NH or CH₂.
 8. A method of generating an electron spinresonance enhanced magnetic resonance image of a sample, wherein theimprovement comprises introducing into said sample a magnetic resonancesignal enhancing amount of a compound as claimed in claim
 7. 9. Amagnetic resonance imaging contrast enhancing composition comprising aphysiologically tolerable compound of claim 7, together with at leastone pharmacologically acceptable carrier or excipient.
 10. A radicalcompound of formula Ia as claimed in claim 1, wherein each Ar¹², whichmay be the same or different, represents a 6-membered carbocyclic ring.11. A radical compound of formula (Ia) as claimed in claim 1, wherein Mis a water solubilizing group selected from the group consisting of:optionally hydroxylated alkyl or oxo-alkyl groups; optionallyalkoxylated alkyl or oxo-alkyl groups; R⁵ ; COOR⁵ ; OCOR⁵ ; CHO; CN; CH₂S(O)R⁵ ; CONR⁵ ₂ ; NR⁵ COR⁵ ; NR⁵ ₂ ; SO₂ NR⁵ ₂ ; OR⁵ ; PO₃ ²⁻ ; SOR⁵ ;SO₂ R⁵ ; SO₃ M¹ ; COOM¹ ; --(O(CH₂)_(n))_(m) OR⁵ ; --CX(CHR⁵)_(n) X; CH₂R⁸, and SR¹⁰,wherein R⁵ represents a hydrogen atom or an optionallyhydroxylated, optionally aminated, optionally alkoxylated, optionallycarboxylated alkyl, oxo-alkyl, alkenyl or alkaryl group; M¹ is oneequivalent of a physiologically tolerable cation; n is an integer from 1to 3; m is an integer from 1 to 5; R⁸ is a hydrophilic R⁵ group; and R¹⁰is a group R⁵ or an alkyl group optionally substituted by one or moregroups COOR⁵, OCOR⁵, CHO, CN, CONR⁵ ₂, NR⁵ COR⁵, NR⁵ ₂, SO₂ NR⁵ ₂, OR⁵,PO₃ ²⁻, SOR⁵, SO₂ R⁵, SO₃ M¹, COOM¹ or --(O(CH₂)_(n))_(m) OR⁵.